[BlackFly]

Katex renders to MathML (either server side or client side). Generally people want a slightly more fluent way of describing an equation than is permitted by a soup of html tags. The various tex dialects (generally just referred to as latex) are the preferred methods of doing that.

[mr_toad]

Server side rendering would cut out the 277kb library. The additional MathML being sent to the client is probably going to be a fraction of that.