What is it you don't get? The parent post clearly states why this can have performance costs. Other modern frameworks like e.g. Svelte solves rendering without making templates JS.
They are overstated. You are not building Photoshop in the browser 99% of the time. Dev productivity should have a higher prio => everything in JS and nobody needs some FE VM with bytecode (wtf, I mean when we already talk about Ember, Ember interfaces are not really the fastest one despite having their own small VM).
This is what I don't get, sticking to the past and requiring stuff which doesn't make sense.
Sticking to the past? You talk as if JSX is the final solution in dev productivity, after which nothing else is even worthy of consideration. JSX has pros and cons, as does e.g. Vue's and Svelte's templating approaches. Something even better will surely appear, or already has.
