Elaborating ways to use this seems to me possibly undesirable, dev experience–wise. Anecdotally, I know some slice of devs avoid it & it's often brought up as one of the difficult parts of teaching/using JS (even came across that recently in digging back into React and their motivations for moving to hooks).

I also personally, but maybe only me, worry about PFA quite a lot. It's such a fundamental shift to decouple argument order with the order in which they are provided and I'm not certain there are use cases that aren't achievable by other means / are so common that they are worth the syntax cost / inscrutability trade-off. Even the example of memoizing and expensive operations could be addressed with (expensiveOp) => (a, b) => { .. }