As you say, the fact is that we've got all of these standards that can't be be changed without breaking the web. Those standards were also first created for a different time, so it's not surprising that some assumptions turned out to be poor.
As a result, we've ended up in a place where tools treat those standards as compilation targets. This isn't a bad thing per se but it does lead to a lot of complexity in the tool chain.
I think part of why I like tailwind is that it almost feels like I'm using plain old CSS. I get the same amount of flexibility (as much as I need anyway), but I don't feel like there is some great abstraction in between me and the styles I want the framework to produce. At the same time, it's quicker and easier to use.
Anyway, I'm aware it's a pretty divisive tool. I see a lot of strong opinions about it on HN!
EDIT: grammar