Plus $2.5 to Reddit, means that apps need to charge $3.60 before 30% App-Store fees. But the app developer also needs new infrastructure to handle the billing, payment, and tracking, between end-users & Reddit along with their existing overhead. So the current $1/month aka $0.70/month after fees they're operating on likely isn't sustainable.
So now we're looking at $3.60 to Reddit + the existing $1/month = $4.6, but also all this new payment/billing infrastructure. Could easily exceed $5/month which frankly nobody is going to pay, and then get all this done in just 30-days even though that date is completely arbitrary from Reddit's end.