It doesn't really matter what RUSE this is under. If the purpose of the site is to exchange or build links with other members, then this is absolutely not allowed and Google will have zero issues penalizing your site for using a service like that.
Google has penalized thousands of sites before and they will do it again.
If you participate in public networks, you are setting yourself up for complete failure.
The ethics of people who set these types of networks up, are absolutely disgustingly bad.
The absolute worst scenario I can think of, is if they would be marketing these services as "white hat SEO" which usually "whitehat" techniques have little to no risk. But, unfortunately, because it's so incredibly easy for the engineers at Google (which is a company worth more than half a trillion dollars) to tie these networks together, a service like this is actually insanely risky.
The people who create these networks, should already know from experience, that Google has absolutely no problem, ruining thousands of businesses because they participate in public networks for the purpose of link building.
Real SEOs would NEVER use these types of networks to build links to their sites. So the owners of these sites are relying on the ignorance of regular people to line their pockets.