I’ve thought about what you’ve brought up in the past. I’m not starting my own forums, and two, we can stack multi-faceted discounts to attenuate to more types of people and three, most people interested (designers, students, business people) aren’t going to waste their time trying to argue during their work hours. Four, paying based on success is already how royalties and stock options for employees work, so if you already accept stocks and royalties as an economic concept, there’s no reason to reject bracketed income models too. And, if you already accept discounts for students, there’s even less of a reason to reject the concept.
If you’re the type of person who’s up in arms about a few dollars, probably you’re the kind of person who needs some kind of discount.
In that case, you’d probably get at least one of several possible discounts for being a sole proprietor or small agency rather than a larger business that’s already vastly successful.