I guess you could do it that way. You'd need a third party landing page to sell it though whereas the "you don't have access" page could also function as a sales page for paying to access if it's officially a function of reddit. Where you'd give mods the ability to give a bunch of reasons people should pay for access.

I bet the first people that pick it up are sex workers. Essentially it's an Only Fans model for subreddits.