[safety1st]

> I don't think the motivation of Google and Meta was datacenter costs, though I could be wrong about that.

Have you forgotten that these are profit-maximizing companies? Why do you think they do anything? To maximize profits. That is always the answer. If it doesn't maximize profits it's a mistake and they will back away from it.

So for example Facebook either thought that React would increase sales, or reduce costs, otherwise they wouldn't have created it. React hasn't moved the sales needle for them (why would it - they are an advertising company - React has precious little to do with selling more advertising). Ergo it was created to reduce costs. The cost benefit of moving all that compute out to the client is easy to demonstrate and significant for a company of that size.