I think that there are some instances of drag being incidental to the humour - the League of Gentlemen fall into that category, because the writers play all of their main characters and some of them happen to be female. I will never not laugh at Steve Pemberton in American tan tights and a big helmet-hair wig. Similarly, Hinge and Bracket were talented musicians and there never seemed to be anything malicious about their act. I can see why some people might not have liked Cissie and Ada but I thought the fact that they looked nothing like women (and weren't really trying to) was all part of the humour.
On the other hand, something like Mrs Brown's Boys offends me because the "humour" depends on him being dressed up as a woman. Oh, look how hilarious it is when a middle aged woman says feck a lot! Tee fucking hee. There's nothing clever about it, it's just a lazy, one-note novelty act.
The Ru Paul style drag queen stuff is so obviously offensive to women that I can't fathom how it has become the sort of cosy teatime family entertainment that can be constantly referenced during Strictly.