How can there be no ads? Because your admins are paying for the servers and run them as a hobby. It's not crazy expensive, but it does take up free time. They still do it because they enjoy the communities that develop. These instances are free with no ads because nice people are running them as a gift for you because they like you. Now, is that better than Facebook's or Twitter's business model or what?
@lambadalambda I don't think it is comparable because facebooks/twitter business model is revolved around profit.
@semerenkov It's still comparable because it delivers a similar 'product' to the users, just with less of the user-hostile stuff (tracking, ads...).