Yes. All it does is that you give it a vaguely defined thing and it checks if that thing is of a certain type (a Promise in this instance). It's something that could have been written and tested with some dummy values in 10 minutes tops, but no, we need to slap this into a library, upload it for all to use, and when it brakes it breaks everything depending on it.
Mostly yeah. There's a thing called dependency hell, where you download something and it has a bunch of dependencies, that have a bunch of dependencies of their own, that have a bunch of dependencies of their own, ad infinitum. This is how you get those huge download numbers for something this basic.