Well some of us have more skills on an alts actually. My dk tank is actually and alt, my main is a holy priest.
My alt is more geared as He is needed more by my guildies.
As for the no alt thing, I understand, yet still disagree for certain reasons.
Not everyone uses a guild for gearing up. Just because it's an alt doesn't make that toon a carry or that they're only joining a guild for gear.
Many prefer to put an alt into various guilds, so they can actually scout for the guild they want to put their main in. I will always apply for a guild with my alt, because if they can't respect my lower geared player, then I'm not bringing anything better geared into the question, for they themselves just have gear on the mind.
And when gear is the only thing you worry about, you're no different than the average fail pug.
Oh i'm the failtard that suggested the naked raid on orgrimar funky, and joined in.