Earlier quoted context omitted.
I wonder how much of this is just the industry maturing/specialising. We don't think it's weird that most people don't mill their own flour when they bake bread, so long as the quality of the flour is good enough we're happy for someone else to do it for us. In the same way most people/companies don't really need to care what hardware their application runs on, only that it meets some bar of quality/cost that's appro…
If you need to have your baked goods constaltly, you will be better prepared with many flour providers in case of that one provider does NOT LIKE YOUR RECIPE and stop selling the ingredients to you... Or get your own flour mill. So, not a ideal analogy...
The sibling comment pointed out that vendor lock in can be a problem which I agree with, but I think for most of the industry that's a problem of protecting yourself from predatory price hikes/services being deprecated rather than the problem of actively pissing off people you need.