DC's minimum file share limit can be easily circumvented, if you are not using the official client, since some of the open-source clients don't play by the rules.

With gnutella it's even worse. There are literally dozens of different clients and many of them are either not developed anymore or their developers aren't even willing to adopt to those rules, so I think no, it's not possible. There'll always be anti-social people on the network, not sharing any files or spamming the network with queries.