it's literally what steve ballmer was trying to tell you about all those years ago. developers, developers, developers. if people want to make your site better for free, let them.

do you charge the goose to lay its golden eggs

if you are a platform, like reddit or twitter or windows, people don't come there for the platform itself. they come there for the things people make for it. historically, that's "you (well, OEMs and big businesses, mostly. microsoft doesn't care about selling Windows to individuals) buy windows because you want to run Office and Outlook and video games and whatever else people have written for it. you don't go to Twitter or Reddit because you enjoy clicking on the buttons there, you do it because other people put things there you want to see. you want to make it as easy as possible for the people who already want to give you their valuable shit for free.