&gt; <i>browser-based CSS, one of the simplest and most reliable parts of the web development stack</i><p>This is absolutely ludicrous. CSS is weird, complicated, and insanely unreliable. Sometimes it&#x27;s hard to figure out how things will work when just reading the standards, and then browsers all have incomplete or buggy implementations of the standards.<p>I&#x27;m not saying CSS in JS is the answer, but CSS is broken enough that we&#x27;re already using tons of not-CSS solutions to write it.<p>&gt; <i>vendor lock-in built-in</i><p>I don&#x27;t understand how using an open-source library is getting locked into a vendor. You could have made the same argument about React, but there are already frameworks that implement the React API. Why would this be any different?