I can't think of any professional UGC platform that hasn't developed some version of a preferred partner program at some point. Microsoft paid app developers to

I can't think of any professional UGC platform that hasn't developed some version of a preferred partner program at some point. Microsoft paid app developers to develop Windows Phone apps, YouTube was paying creators to onboard onto their platform, Mixer famously paid Ninja a ridiculous amount of money to defect from Twitch etc. It's an absolutely standard growth tactic. Different partner programs differ in the degree that they're open about the details of the program but, in general, they almost never list who the exact recipients are and quite often come with quite onerous NDA requirements even to be considered. I know for a fact that there was at least 1 YouTube program that was handing out check sizes up to $100K USD that I've never seen any reporting about in public sources but was quite well known within a specific YT vertical. How unethical this is is up to you to personally determine but I don't think substack has done anything that is outside the norm of pretty much every other company of that plays in this same space.