When I worked at AWS, the majority of customers who thought they had database backups had not tested recovery. The majority of them could not recover. At that point, RDS sells itself.
The other huge middle ground here is developer competency and meticulousness.
People radically overestimate how competent the average company writing software is.
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.