Uhm, are these supposed to be arguments against me?
That it's common for all of these sites, who have massive surveillance and SEO structures built into them, to have gigantic stylesheet collections doesn't change the fact that they are bloated nightmares of code.
If I said, "filing taxes is a nightmare", and you said, "oh yeah, but what about all the other people who file taxes, some of them even more complex than yours?" That wouldn't change the fact that filing taxes is a convoluted, intentionally obfuscated, Lovecraftian construct, summoned forth from the depths of Hades itself.
The large stylesheets have nothing to do with the SEO bits.
They have to do with having a site with a wide variety of different-looking pages and wanting to have a single site-wide stylesheet, instead of having dozens or hundreds of smaller stylesheets. Whether that's a useful thing to do or not obviously depends on how your maintenance for the site is set up, how your CDN works, and probably other things I have no idea about; design of this sort of site is not my area of expertise.
And while I agree that all of these sites have a lot of complicated styles and scripts going on, I have a hard time believing that a site of the sort I just described can be created without ending up with a fairly complicated stylesheet.
If your position is that having such a site (variety of different kinds of pages) should be a non-goal, I can't agree with that: there are plenty of reasons to want a site like that. If the argument is that having a single stylesheet to rule them all in that situation is bad for maintainability, I don't have a good response: as I said I've never maintained such a site, so I don't have a good feel for what the maintenance tradeoffs are.
That it's common for all of these sites, who have massive surveillance and SEO structures built into them, to have gigantic stylesheet collections doesn't change the fact that they are bloated nightmares of code.
If I said, "filing taxes is a nightmare", and you said, "oh yeah, but what about all the other people who file taxes, some of them even more complex than yours?" That wouldn't change the fact that filing taxes is a convoluted, intentionally obfuscated, Lovecraftian construct, summoned forth from the depths of Hades itself.