Sounds like, based on the comments, these limitations trace all the way back to the beginning of CSS support in IE. It was probably reasonable at the time and I’m not really sure who could’ve expected the explosion in complexity that ended up happening later; at the time stylesheets were used in a much more straightforward manner - I remember some sites let you select between multiple stylesheets!
It's a giant pain but if you're running highly complex sites that have to work in old IEs then this may be something you want to implement. Often you see the need for stuff like this when pulling in frameworks like Bootstrap, etc.
Haven't had to do this for years (thank goodness) but depending on market, etc. IE9 still rears it's ugly head sometimes.
I ran into this when we concatenated our css so all the styling would load with one round trip. No warning in the console, IE just ignored the rules after the 4095th. And because the concatenation was a build step you wouldn't normally see the problem in a dev build. Good times.
