True, there were tons of crappy hardware still in production at that time. The first job I had out of college consisted of crappy 3Com hubs (not switches) so something like Norton Ghost could take down the whole network since multicast would get flooded everywhere. Nowadays this is a less of a problem as hubs are long gone and most switches have IGMP snooping by default and would only forward mutlicast frames that someone wants.

A bad client can still cause problems though, like sending a high rate of multicast packets with a TTL of 1.