In practice when people use ||, they do mean ?? (whatever its spelling). It just so happens that most of the time, it does what you want, because you happen to not be dealing with Booleans. But the semantics you mean to express is not about "truthness", but about "nilness". And occasionally you get bitten because false does exist, and behaves differently.

In this article, we saw that an RxJS Observable can act as a drop-in replacement to a Svelte store. This is probably a coincidence, but this makes it very pleasant to work with.