There are folks that have been posting regularly here since 2010, and continue to do so even though the name has changed.
(all things Plants changed to NGA)
Some folks post on 2 or 3 sites occasionally, but read everyday. Usually when you see a large number of views, people look at a post, if they can help, they post. If they can't be of help, they continue to watch (view) to find out what the answer may be.
The Admins here started their first gardening site back in 2000/2001 and there are folks here, posting and active that started out on the original site and have been active since 2000.
I think it depends on the site and the way it is operated that keeps members coming back year after year, as I certainly hope you will.