Just because it's money? You're also spending your time, effort, attention, and opportunity cost.

Is college meta because you spend money to work for free with people who also spend money, while learning from people who get paid money to teach you?

You're probably more used to services that monetize with ads, and encourage quantity of accounts at the expense of quality because it's good for their numbers. Nothing meta about one or the other.

No, just because it's a recursive service. A feed where the feed is full of people talking about the feed. At least, last time I checked.

Edit: And, suspicions are confirmed: http://adn.loqix.com/appwords.17:00-03.10.2012.png