Different networks have different characteristics & have their own problems such as queueing.

The reason downld hosts is limited is to keep those hosts upload slots available for other people. Otherwise a few would downld from 10's of hosts but other people may find they can't connect to the same file hosts because there's no available slots. So it's basically to keep all things in balance. I hope you understand the concept. Gnutella's development is to try to keep things flowing so people are able to connect quickly, to find search results quickly, to downld at reasonable speeds, to connect to hosts for downlds without being continually plagued by "Busy Hosts". I believe WinMX suffers this issue where people may have to wait a long time in a queue to get files. That's something gnutella tries to avoid by keeping downld slots limited. So then there's a fair share to go around.