If you are reliant on a third party for your livelihood, then consider ways that you can change that; what if overnight they changed their rules and you lose your access to them how would that affect your business or your livelihood?
Perhaps you are an employee who got made redundant, perhaps you were reliant on Facebook and they change their API access and your business no longer has access to the data it needs to function, perhaps you relied on MySpace and it just died on you!
If you rely on some other company for your livelihood, at some point, they can change that relationship and you can be left stranded.
So, if you can avoid it, don't build your house on somebody else's land.