FWIW, I don't think it's spez who's asking for that; he's simply the conveyor of the message.
I'm pretty sure this is a finance constraint imposed by underwriters/financers of the IPO, who want to see all the revenue with reddit and not with third parties. (I also think Twitter's similar move was at the behest of $ people since Elon borrowed money to buy the company.)
Since spez said that one objection was that other people were making money where reddit wasn't, one thing I'd have been okay with is if the API worked only for those who were reddit premium. (To be open, I was already paying for the lowest tier of premium.)