Our clients integrate with all manner of public and private APIs and this is how we build every one of them. The flakier the provider, the more the gambit pays off.
You don't have to build the whole API, just the parts you use. And you don't have to implement the real service at all. It amounts to just a bit more overhead the first time you use a new API, but that's dwarfed by the amount of time your team spends learning how the thing "really works" anyway.
Imagine what an integrator who works with public cloud would have to do?
Now imagine that integration with three different public cloud is only a small fraction of what our software offers...