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.
Red Fightback contains Caucuses. The purpose of a Caucus is to provide a forum for members that experience a particular form of oppression to: develop the party's positions relating to that Caucus; advise the party on matters relating to that Caucus; and provide political education, support and community for members.
Currently there are four recognised Caucuses:
Racially Oppressed Caucus
Past & Present Sex Workers Caucus