Putting aside the fact that replication and backups are separate operational topics -- even if a company has no competent backend engineers, there are plenty of good database consultancies that can help with this sort of thing, as a one-time cost, which ends up being cheaper than the ongoing markup of a managed cloud database product.

There's also a big difference between incompetent and inexperienced. Operational incidents are how your team gains experience!

Leaning on managed cloud services can definitely make sense when you're a small startup, but as a company matures and grows, it becomes a crutch -- and an expensive one at that.