Otherwise, its like using Arrays or Lists instead of Maybe. Hope that clears up why its "bizarre", but if not, its because the contract is not restrictive enough.
Example: `let x:Observable<Row[]>`. Does this generate a single event with all the rows? Or does it do row batching? No idea. Can I consume both the same? Not really, depends on the use. e.g. if I want to sort the items, I'd have to implement merge sort for the second case.
Given any Observable `obs`, you can consume it with `obs.take(1).subscribe()` instead of `obs.subscribe()` and then you'll be sure it only generates one value per subscription.
But in practice the generation of multiple values in itself is rarely an issue to worry about. Often you just want to drop consecutive duplicates, there's an operator for that: `distinctUntilChanged`. You can also end an observable based on a timeout.
Multiple values emitted is a pseudo-problem, and often your programming becomes more powerful ("does more in less lines of code") by using that capability.
the bizarre meme is that they are 'replacements' for promises, they are really intended for (as you rightly put it) push streams which is a different, though occasionally overlapping, use case then promises.