Why give money to Facebook, Google, and Twitter when we can give it right back to our customers? They’re better advocates for Basecamp than any ad we can write. They’re not a platform, they’re people who know other people
Paying customers, not paying Facebook, Google, or Twitter.
Jason Fried

In the (internet) world where ads seem to always find their way into interrupting people by adding noise when people and their attention starts to flow in big numbers, this makes a lot of sense.