What does it actually do? Yes, I know what a backend is - and the backends I write have hundreds to thousands of lines of code that do very specific things. How can that be eliminated? What types of applications can be built with these tools?
Yes, you can always build a better backend yourself if you know what you're doing, or you can go from zero to having a proper auth (username/password, 0auth providers, one-time emails, multi-factor) to plug into by running a binary.
Unlike Firebase, you can run it anywhere. Unlike Supabase, you don't need 10+ containers to do so.
It might not fit your use case, which is fine, but there are a lot of use cases it does fit, and my original point was that it’s more than you might think.
I wouldn’t really describe it as niche and limiting though, that sounds quite dismissive of what is actually a pretty impressive piece of software.