How did Facebook force them to add those people as friends?
No, facebook the company did not force them at gunpoint to add their parents. That's correct. There are degrees of pressure, yes? If someone found them too much to put up with, is it unreasonable to accept the term 'forced' as apropos?
[EDIT: to the people downvoting this, the subtleties of language matter. There is a big and specific difference between concepts like "encouraged", "presssured" and "forced"]
The definition I cited was for illustration. Since when does backing up you point with a definition mean you're being slavishly robotic?
Since you're trying to imply my usage of the term is narrow and unrealistic, what's the different notion of "forcing" someone to do something that would make it true that Facebook is forcing people to friend others that they otherwise wouldn't want to?
From a Facebook designer's point of view, the UI/UX most surely is intended to be "encouraging". But it may also be the case that for some users, the social dynamic may feel particularly oppressive.
I'm explicitly stating.
So perhaps loosen your grip and understand what the OP was saying?