Sure, but don't expect PvE Guilds to carry you through MC/Ony/BWL when you're throwing Fireball at bosses that are immune to Fire. And don't come complaining when no PvP Guilds will accept you because you insist on playing Prot Warrior for Battleground*.
Those who only cares about their own experience in Vanilla either runs solo, or they will only have the experience of being rejected and denied.
*Unless they are only doing WSG and you're the designated flag carrier.