The thing about the pipeline operator that strikes me is how toylike all the examples are. Look at this article for example - it’s a bunch of examples of adding and exponentiating numbers, as if you couldn’t do that already in a single line of code.
My suspicion is that once you move away from toy examples, most pipeline operator use cases are already covered by chaining class methods on classes. I suppose you could argue that the pipeline operator allows you to operate across multiple different data types, but I further suspect that handling many different data types with a single function is an annoying thing to get right and this won’t come up in practice all too often.
To be fair, the case of pulling in only the methods you need on rxjs seems somewhat useful… but do we really need a whole new operator just for that? And isn’t that the point of ::?
I think one of the use cases is that it's easier to have a series of functions on immutable data compared to chaining classes. Considering JavaScript may get immutable data structures at some point, this would work well with them.
There is also the fact that JavaScript supports different types of programming, functional being one of them. Having a pipe operator helps you to make very clean and readable functional code.
Edit: the article also mentionned that methods can't be tree shaken. That's another improvement.