The most interesting thing about css-in-js is its critics. Most criticism of css-in-js is very shallow and essentially boils down to "that is not was I was taught". It usually comes with oversimplified statements and a touch of name calling.
Brogrammers couldn't wrap their megabrains around not-a-real-language CSS, so decided to reinvent it and fight against the web platform for their own convenience. Who could possibly have predicted it would be crap for users, and would need expensive surgery to drain the festering pus?