> Now, the above mentions one or more third parties.
Exactly.
> Whether or not something constitutes a 'real' business does not hinge on that business' dependencies or any other risk factors.
If a business is created with the explicit goal of being in the position of building right on top of another business for which there is no alternative, then I doubt the right of that business to call itself an independent business.
Sure, no business is without risk, there are always factors that increase or decrease the risk. You should always be trying to minimize those risks, and if there is one thing that is a huge red flag for investors or buyers then it would be a dependency like that.
The 'What if you get cut off' question is absolutely unanswerable. If you manage to get it to the point of a contract with termination clauses and such then that's a different story, but until then, to just build your enterprise on top of an API and hope for the best is not a good long term strategy.
Your point about google is well taken, I'm happy to report that my business depends for less than 2% of it's traffic and income on google, I wouldn't have it any other way.
Of course there are numerous examples of companies that did great building for instance software on top of the microsoft platform, but worst case there would have been other operating systems that they could have ported their software to in case microsoft would go under.
If a company like twitter or facebook would go under or decide they no longer want you or that you become too much of a threat you're done.
Instantly.
And you don't even have any recourse, simply because you never had a contractual right to be there in the first place, after all you use an API at the providers discretion, and nowhere in their terms of service does it say that you have a right to access, no matter how popular or profitable you are.
That's not the same as being in a business relationship, even about something as mundane as buying and selling pencils.
The self sharpening pencil, by the way, has been done:
http://en.wikipedia.org/wiki/Mechanical_pencil
And, more in jest:
http://www.pencilthings.com/product.php?productid=100664?utm...
But they didn't put any pencil sharpener producers out of business, though I suspect the typewriter and the word processor may have caused a few of them to find different sources of income.