This list is an absolute gem in finding what are the trending state-of-the-art open source programs. I have found so many cool open source projects I feel addicted to browsing more..
By selling advertiser space via their website and newsletter they encourage people to sign up for. You can tell the one in the OP is focused on that in their advertise page https://openalternative.co/advertise and the ad for the owners other platforms which help people monetize list/data table sites like this.