Well, yes or no, or just plain maybe. If the lack of a filter results in crap getting into the needle valve and stopping it from sealing, it will have effectively caused the carburettor to flood.
In that case, the leak would have been prevented by the filter.
I have to work at remembering to shut off the gas now. I occasionally ride the OL's new fuel injected bike with no petcock, no choke, no nothing. Just turn on the switch, wait 4 seconds and punch the starter. A real easy way to develop bad habits.
