No it's not. It's usually massively saturated APs, an overloaded DHCP server, or too small a pipe, as the linked article said. That, and even one jackass can really hose a system if resources aren't hardened at all (to avoid spam requests, spam AP hopping, etc.), and often they aren't as it's "just temporary". BYOA has become the name of the game for me: thank god for wireless broadband.