Since this phenomenon, of leaders who are in fact primarily mascots, is common to both Labour and the Tories, you'd be right in thinking that it has a common cause.
A large segment of political news in the last few weeks has been devoted to the contest for the position of leader of the Conservative Party, and therefore Prime Minister. This is, we are told, a decision that is of huge consequence to us all. The mainstream press is talking about little else. And yet communists do not seem interested - why is this?
Let's start by asking what the Tory boss does. On the one hand they are leader of their party: they ultimately oversee the generation and execution of the party's strategy. On the other hand they are a mascot of their party, a promoted public face to communicate the "vibe" the party has chosen. It would be an oversimplification to say that leadership is absent from the role of Tory chief: they can exert some direction and push pet projects. But, on the whole and in the long run, the position is much more one of a mascot. Looking at the recent history of Tory bosses provides some evidence for this claim: Cameron (and Osbourne) were portrayed as elite management, technocrats making hard but necessary economic choices, and collapsed once they became the face of grinding austerity; May was portrayed as an iron lady capable of securing a bold new economic future outside Britain, and collapsed as the impossibility of that project became generally evident; Johnson was portrayed as a showman with flashes of brilliance that would cut through basic political contradictions, and has collapsed after a failure to handle either COVID-19 or the ensuing poverty crisis.
We can also draw evidence from the behaviour of candidates in the leadership contest. Broadly speaking they are not setting forward theoretical and political positions; what positions they do take are vague and schematic, and (as we shall see later) are unlikely to be implemented in any way. Instead the general behaviour of candidates is to cluster around particular points of "party brand", all fighting to be the one with the best statement on personal integrity, or with the definitive phrasing to entrench transphobia. These candidates do not seek, on the whole, to express a vision or project through the party: they seek to best express the party's currently needed brand in order to win the contest today, and win a general election in years to come.
This behaviour is not specific to the Tories. Remember the Starmer - Long-Bailey contest for Labour leadership? The two ended up trying to stand on top of each other over the same policy positions, as each tried to better encapsulate "Corbynism in a suit", the party brand sought at that moment. Starmer, the more potent suit, won that contest, and has further emphasised the suit and suppressed the Corbynism as the party brand transitions back to New Labour. The fate of Starmer's ten pledges to the membership - entirely abandoned - illustrates the earlier point that candidate positions are largely for show and unlikely to ever be implemented.
Since this phenomenon, of leaders who are in fact primarily mascots, is common to both Labour and the Tories, you'd be right in thinking that it has a common cause. Both the Labour and Conservative parties in Britain are bourgeois parties: this means that both are concerned with the preservation of capitalism, with upholding the dominant position of capital, with continuing the exploitation of the global south, with accelerating ecological devastation. As this list makes all too clear, this capitalist system is beset with contradictions - in fact it is wracked by them, and increasingly struggles to go on. Any genuine political project must attempt to address these issues, and so must address their roots in capitalism: the only revolutionary position is socialist. But as bourgeois parties a revolutionary socialist position is obviously unacceptable to Labour or to the Tories, so they are forced into this performed brand-first pseudo-politics: they refuse to treat the underlying disease in our society, so they must try to avoid recognising its symptoms, and therefore their only remaining option is to present the terminal prognosis through the doctor with the "right vibe" for the moment.
Neither party is ignorant of its role, though many of their less intelligent mascots may be. We can draw evidence for this from the demise of Corbynism: a project to introduce the mildest forms of an actual political project into Labour, addressing some of the symptoms of capitalism while still falling far short of a revolutionary socialist or anti-imperialist position. Even this dilute attempt drew immediate opposition from across the British state: government, media, military, and Labour internal apparatuses all rushed to repress it. And this all took place without the Corbyn faction achieving control of government: I do not think anyone can seriously contend that an elected Corbyn government would have been allowed to implement a fraction of its programme. The purpose of the Labour party, to capture radical movements and suppress them, was played characteristically here.
In describing the pseudo-politics of bourgeois parties, I have left out one important element. This element is fascism, the only move available to capitalists when the contradictions of capitalism become unsustainable. In a fascist mode, petty-bourgeois insecurity and mass discontent are marshalled against a chosen target, often a national or racial minority, whose further oppression is turned into the foundation of a temporarily stabilised and more exploitative configuration of capitalism. It would be wrong to think of fascism as a totally separate tendency to the bourgeois politics we have been discussing: outside of entirely fascist regimes, we can observe how more fascist elements are deployed and then drawn back to allow their changes to be locked in, refined and institutionalised. In recent examples we have New Labour codifying and industrialising many of the fascist innovations of Thatcher, or the Biden administration rationalising and formalising those of Trump. Shining a light on this link is the virtue of the old third period slogan, that "social democracy is objectively the moderate wing of fascism": the objectives of the two tendencies align entirely.
So what is the take-away point for the Tory leadership contest? Or on Keir Starmer, or for the next bourgeois election? It is not that these things don't matter, because of course they have some influence. Instead I want to emphasise the point above that these contests and elections are far more an indication of the current state of British capitalism, an indication of the desire for fascism, than they are an intervention towards or away from it. For this reason, socialist and revolutionary politics can most effectively be carried out working beyond rather than through electoral politics. And for this reason, there is no point in writing a thousand words on Rishi Sunak's political goals (or Starmer's, or whoever's): these goals themselves simply aren't the determining factor in anything of significance.