This is exactly why I started working on 20-things.com with a firm stand on not doing what Reddit has been doing - pushing people to mobile app in order to be able to track and show them ads (adblockers won't work in the app of course). How can I achieve this? By limiting the community size to a certain number of people so that it can stay self-sustainable. This could be a few thousand users, and then the door gets closed to new registrations.