People using jQuery improperly is not something wrong with jQuery. jQuery is perfectly fine for large web applications, you just need to organize your code properly, with something like a MVC and ORM layer.
I'm also very skeptical of the dozen-odd undocumented "extensions" to the selector language. They are useful, but tend to tie you to jQueryisms. I didn't realize for a long time that :first was not valid CSS3.
Now that we've gone all the way down the pedantry slide, have you anything of value to contribute, or was that it?
If you want to pick on something that claims compatibility, try Sizzle itself - http://sizzlejs.com/. In that case, you'll find a summary of alterations right at the top of its documentation https://github.com/jquery/sizzle/wiki .