> I've seen some custom PHP production codebases with plain css and jquery doing its thing with 1x10^6 plus weekly traffic. I've worked on plenty of those. I'v

> I've seen some custom PHP production codebases with plain css and jquery doing its thing with 1x10^6 plus weekly traffic. I've worked on plenty of those. I've handled more traffic with uglier shit, too. This isn't a performance thing, nor is it a premature optimization thing. It's about developer productivity. Refactors are faster. Components are easier to break down. Bugs are easier to catch at compile time. Some classes of bugs are entirely avoided. A LOT of UI logic makes a ton more sense when written declaratively (as React forces you to), than imperatively. And none of that is even getting into the realm of how much easier it is to find devs who will work on a ReactJS codebase (and even more so, will be happy to do so). My field Python experience surpasses my Typescript/React experience easily 50x. And yet, I'll be much faster at picking up a new client's React/TS codebase than their equivalent Python one. The productivity gains are real.