The implication here is that, "...or else users won't participate." Which I agree, needs to be justified. You see this kind of talk a lot when power imbalance

The implication here is that, "...or else users won't participate." Which I agree, needs to be justified. You see this kind of talk a lot when power imbalances exist; the person with no power tries to speak on behalf of everyone involved who they think believes as they do, in order to try and stand against the existing power structure. Sometimes it's highly effective (actually appointed or even de-facto leaders of movements/groups), other times it's kind of laughable and presumptuous. Without justification, this is the latter. That said, I bet there probably is justification, if the author bothered to look for it or provide it! I would suspect it's true that users will not make use of a site like Reddit nearly as much if the content isn't then made available for use "as they wish".