There's also a lack of standard server-side-rendering support. From last I looked at it, some of the web component libraries have their own SSR support, but that only works with web components authored with that specific library, negating the supposed universal compatibility of web components, and they involve using heavyweight simulated DOM libraries on the server. I'm not going to bother with something that doesn't take SSR seriously when React aces that so well (especially with the newer server components support) among other things (like giving you a code model that ensures by default that updating a prop at runtime causes the same result as setting it on creation).