[tofof]

It's unfair to claim that styles are removed "at random." And even if you're only using one framework, you'd still almost certainly have unused styles that can be pruned.

Generally, you'd want tools in your build pipeline that do this automatically (see my other post). Doing so solves all your objections. You're free to later use styles that you hadn't been using -- they're still there in the source CSS, so when you rebuild, they just don't get pruned out anymore. And those tools don't just analyze a single html file, they examine your entire source tree, so you don't have problems with styles used on some pages but not others.