Because Gnutella is a Kazaa type network where everyone (newbies) is welcomed. BT and ED2K networks are a bit ellitic in the way that they require users to be quite advanced at the network levels (high IDs, port configuration). If LW or Bearshare would limit download by amount of uploads, much of the network would dl nothing (thus leaving). 70% of the gnutellanetwork is firewalled and thus provide much less upload opportunities. (That should change in LW 4.2 with firewall to firewall transfers). Also a credit system à la eMule is problematic as far as implementation accross clients is concerned (Gnutella has the biggest variety of different clients). Better just lobby in shareaza forums to either stop using gnutella or start being fair, like trap_jaw is doing over there. I personnally think they should drop gnutella support (as well as ED2K...). The problem with shareaza is that it is hard to convince their supporters as they are a LOT (in active fans) supporting the multinetwork idea.
For now I prefer lobby against Morpheus, it is less time consuming and more benefical, IMO
