You're right in that there wasn't a straight man in the sense of Mortimer to Reeves early on and they weren't Morecambe and Wise either. It only really lasted as a passing fad for a couple of seasons, although they did attain almost rockstar status (Viz readers will recall 'Student Grant' binning all his Reeves and Mortimer stuff in favour of Newman and Baddiel).
When Newman peeled off he started to focus solely on political standup (a more bookish Mark Thomas, basically) and his first novel sold OK because of who he was but as I recall it wasn't really up to much and anyone especting "Stoke on Trent? Bent!" would have been much disappointed.
I watched the 'Wembley' show again for the first time in years as a result of this (External Link/Members Only), some of Newman's non-PC routines would land him in no end of shit with the woke brigade now.
I forgot about Reeves and Mortimer another great double act, but also good solo, but I don't see either as being stand ups in the classic sense. Also Hale and Pace were criticised for having two straight men, I know they've been mentioned before, but they benefitted from great writers and have a few classic sketches under their belt namely Yorkshire Airlines, the grim Mr Chips parody and alcoholics anonymous.
You'll read either Baddiel or Newman were the first comedian to play Wembley this is bullshit it was Sean Lock as he was warm up and on before. Loads of unpc stuff in the 90s just look at some Harry Enfield stuff, even The Inbetweeners wouldn't be made today. What we've got instead is "ironic" disablist humour with Boyle or Gervais mocking "mongs" or dreary shit like Fleabag.
I think for me it's the misappropriation of the word genius. Is Gervais a genius? Not even close I liked the office first time around, no way I would watch it again, his films are on the ok side and I thought his stand up was piss funny around mid 2000s. I think Stephen Merchant is the funnier of the two. Boyle I thought was the funniest on mock the week and he seemed fresh about 15 years ago. Now he became sanitised like Graham Norton who was great on channel 4 20 years ago.
I think genius is a few times in a lifetime thing and most are dead. I think intellectual has become another misappropriated word, but I digress.