Joining clans that only play on one server is pointless and not very fun, of course people who play on one server forever will disagree but it's not much of fun. Knowing samp top clans and playing with them is FUN. Fighting and chilling with ridiculously skilled players is pure awesomeness. Of course, that implies on players who look for competition in samp like myself and few (3 maximum) of PTP regulars.
Point is, if you play only ptp to have fun only and chill with friends then you don't need to join any clan.
But if you are a competition type of a player and wanna do clanwars and clan invasions then I recommend you to look for a clan out of ptp