Limiting the participants in a campaign is a good proposal because the fewer partipants the higher profits you may earn but it is not applicable for ico organizers or the bounty manager because they only need higher amount of supporters so they just accepting who'd want to join.
It is called a marketing but at the end, people who are participating in those campaigns will earn less unless those programs increase the amount proportionally if participants go up. But I don't think they will do that part.
Unlikely, the more people are involved, the more spam on the social networks and that is what they want, their ico will be for many people.
The purpose of bounty is to makerting and the more participants they promote success
It is actually people mistake because they will not ask them to fix certain price for each action on social media instead they will join as soon as they announce as if they will never get again a chance. If no one joins such programs then they will be forced to fix price then you know how much you may be earning at the end of the week.