Like I said... some people. Not everyone. But you have to understand that Lusternia is designed so that guilds aren't just isolated sets of skills, they're organizations - Every time you join a guild, you take some of that guild's time and effort. It's immensely disrespectful and ungrateful towards those people to quit a guild immediately after their skills are made weaker, and go waste the time of some other guild whose skills are now perceived to be 'good', and frankly, I wouldn't accept someone who did that into a guild I ran unless they jumped through a significant amount of hoops.

To answer Ixion's question, a clue-by-four is a notional device used in punishing the clueless.