Because most of the new people who are now registering in the forum are from poor countries. They have no starting capital, they have no jobs, didnt graduate from a university or from college and no career prospects.
That sounds bad, but its a fact.
or you know... it's easy to do so and you're not risking to lose, pretty much, anything? You don't know them in person to say that, maybe there are a few that suite that description, and some probably don't but bounties, as just bounties, are the easiest thing you can do on this forum if you can't join a signature campaign.