HN user
Over 90% of the boards on 4chan are nothing but discussions about the particular subject. The most illegal stuff that happens on these boards is uploading images without permission, yes, it's that bad.
Most people who speak of 4chan in this way, are really just talking about /b/.
I'm not familiar with Angular.js. But I am very familiar with CSS3, jQuery and the Greensock animation platform. Greensock (TweenMax) is without a doubt the best animation platform I've ever used. CSS3 animation gives you nowhere near the amount of fine grain control over animations that greensock provides. CSS3 is great for simple stuff, but for complex reactive timelines it's basically impossible to work with. jQuery is OK for basic things that don't need the performance, but is clunky is feels restrictive.