The idea that some people are using other companies backend systems to build their own company that completely relies on those systems creeps me out.
If I hire a backend developer who creates an API that talks to my DB, then that developer walks away, at least I can continue with my business while I run around finding a new developer. I don't need a new codebase and I don't need to shutdown operations. If a hosting company goes under but I host my own code there, at least I can redeploy elsewhere and get on with life. If I use a BaaS company and they go under/discontinue my hosting/etc then I can neither move, or hire another company to continue the work. I have to start again, and for anything significant, that's probably going to kill my company first.