this blog post and subsequent discussion is literally just about horizontal centring!
I’ve been building websites longer than most (since 1994 in fact) and centring in CSS is definitely not as easy as it was with the <center> HTML. Not even close. If it were, there wouldn’t be this entire discussion to begin with.
I swear the amount of times topics like this come up and yet a small subset of developers, likely Stockholm syndromed into believing things are great, is ridiculous. The sooner people like yourself pull your head out of your arse and realise that the current status quo is unacceptable, the sooner web standards finally mature into something that doesn’t have more footguns than the worst of C and worst of Perl combined.