Animations, even 3d ones, drop-down, sliders, static scroll elements, are often implemented on horrible js with bad performance and accessibility, while trival with a small amount of css.

That's fine, I didn't think you were trolling. But I'm not sure what are you an asking an example for? Do you want me to write up a comparison or just tell you some cases where HTML/CSS is lighter than JS? I'd honestly just recommend building a flashy animation primarily with Javascript and then try and build it using only HTML/CSS. Most of the time it will be easier and more readable to go with the latter, as well as more performant and likely to stand up to the test of time.

There are definitely a lot of times where Javascript makes sense, but what I really just wanted to point out is that people usually default to 'Well I'm already writing tons of Javascript, I may as well write more!' as an excuse to create simple animations or transitions with dozens, or hundreds of lines of code, or bringing in a dozen external dependencies to handle it that also break in weird ways. I'm definitely not a NoJS zealot either -- I've been working primarily with React code full-time in production systems since 2014. But over time I've found CSS to be far more pleasant and faster to work with than testing, maintaining, and/or relying on someone else to do the same thing in JS.