haha dude, such a bad take.
have you ever played/watched or know CS Source before 2010-2011? (Especially before Orange Box Update) Source was sadly a bad game, a wasted game by Valve. broken ass hitboxes, broken ass movement (easiest CS game in terms of movement), broken netcode and hitreg, Source was a shit show, it was for the players that can't play 1.6 well, since 1.6's skill ceiling was much higher than Source ever was, and those players switched to the Source since it was easy as hell and became pro players in CSS. (you can even run and gun in CSS sometimes) that's why 1.6 was much more popular and everyone was playing and watching it, Source scene was also dominated by France, sometimes Germany, UK and NA was winning some tournaments as well but most of the time VeryGames was dominating.
so it's not like "boomers always prefer old stuff" as you say, CSS was a wasted game by Valve, and Valve didn't improve the game. that's why everyone was sticking with 1.6. Of course, 1.6 had lots of bugs as well, wallbangs, and console commands (like interp settings, you can tweak them for your advantage) , but at least in tier 1-2 matches, these bugs and settings that you can adjust via console were not allowed to use and 1.6 required a lot more skill to play rather than Source, I'm not saying Source didn't require any skills to play btw, just saying it required much less skill to play compared to 1.6.
However, I like CSS very much, it was such a good game for Casual players, contained so, so much fun in Community Servers, Zombie, Surf, Bhop and many more gamemodes that created by community had so much fun, it maybe even had more fun than 1.6, but for competetive play, Source failed it, 1.6 was far more superior. I sometimes watched some pro matches too.