For those unfamiliar: this is a backend server you can configure via a GUI, so you can get a working backend with little or no code. It’s great for quick prototypes, MVPs, and simple apps. The concept was popularized by Firebase.
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.
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.