> ReactJS has been a very mixed-bag...

This is a very confused statement to be made, specially after the last decade where React established itself as the de facto way of writing any and every SPA.

Is it yet another example of "there are only two kinds of languages: the ones people complain about and the ones nobody uses."

I think the universe of SPAs that should exist is far smaller than the universe of SPAs that does exist, and the hype around react is largely to blame.

> the ones people complain about and the ones nobody uses

The funny thing is that prior to 2015 "the ones nobody uses" were the academically-designed ivory tower FP languages; perpetually relegated to being a minority curiosity because FP is immensely difficult to wrap one's head around at first, especially if all you've-ever-known was imperative C or VB and (compromised) OOP in Java and C#.

I remember when Google's overqualified design-team for Angular decided that Angular2+ is too good for Promise-based fetch() - instead everyone should be forced to learn RxJS's way-of-doing-things - cue the agony, wailing and the gnashing of teeth.

...I think being forced to live through that experience did 2 things:

1) It forced an entire generation of front-end web-devs (and VB6 refugees) to get familiar with FP-like concepts.

2) It also made those same front-end web-devs swear-off ever using a Google-maintained SPA framework in future.

...which set the stage for the mass-adoption of ReactJS:

1) It made effective use of FP concepts, which many devs were now accustomed-to after having survived Angular2.

2) It wasn't made by Google.