Maybe it's regional, then. Because in my community, hosts and hosts alone tip the staff. I NEVER see a tip jar at a hosted event, and if I did, would think it looked terrible. Hosts would indeed be insulted by guests tipping the staff, as if they considered the hosts too cheap to do so. So someone who went around tipping the bartenders, waiters, and musicians at a hosted event here would probably be seen as a flashy big-shot wannabe trying to get the staff to treat them like a celebrity.
And I agree that it is rude to try to buy yourself better service than the hosts have provided and that other guests are getting. It is sort of like asking if you can pay extra to have lobster instead of the chicken that the hosts ordered.