I'm pretty sure that there is a thread about this topic, but might as well make a new one.
I am aware that many guilds have a 18+ policy which is understandable, because nobody likes an immature player while raiding. If a player who is under 18, but has exceptional gear, skill, and is not annoying would you accept that player into your guild? Let's say there is a player 16 years old who applies to your guild (class is irrelevant) and based on the application looked like a great addition to your guild, would you accept them? Would you deny their application based solely on their age? The guild that I'm in right now took that chance and I'm a main raider now. However there are some guilds who wouldn't even bother looking at an applicant if their age wasn't 18+. Not all players under 18 are immature brats, would you be willing to take the risk?