I am not sure 'API' is relevant. This is a business partnering (supply partnerships, channel partnerships for distribution software platform choice etc.) question, and the logic is the same as the question of whether you should build your business around supplying to Walmart, or become a parts supplier that builds infrastructure to deliver a specific kind of part to Ford for example. Or even companies that specialize in selling to specific government departments. Choosing an OS to build on is a similar decision.

The only thing that makes building against an API different is probably the fact that any fly-by-night operation can set up an API, so you get a lot more choices that might not be around tomorrow. But that problem solves itself because APIs worth relying on are generally the big successful ones.

In general, this risk is not avoidable, only manageable. A completely vertically integrated company that owns its entire supply chain from commodity vendors (the opposite of API) to direct customer sales...kinda a rare and hard thing to build. And getting harder all the time.