[hntester123]

That's an interesting theory. I suspect it is likely to be applicable in many, if not most cases.

Related anecdote: a person contacted me a year ago and asked if I'd be interested in being a co-founder of his startup that would be using $(major_social_networking_service)'s API (as it's main source of information, for doing something that piggybacked on that service's user profiles). After thinking about for a while, I said I didn't want to get into that, and also cautioned him about the risks of relying on another company's API as the basis of the startup, as they could change the rules at any time and that might break his business model.

Interestingly, we've seen events (in the tech news) since then that showed the risks of that approach.

Your theory seems like a more generalized version of my thoughts, and I like it.