A better way to think about it is that these games are designed for - and paid for by - exactly the very few people who want to spend this much on winning a game. Everybody else gets to free-ride on this, and only pay what they want (mostly zero)
So the players who are "paying what they want (mostly zero)" aren't getting a normal but free Diablo game, they are getting version of that game balanced and prioritized around the whales that /will/ be spending the money. The actual customers.
I'd rather pay than "free-ride", because I don't want incessant popups telling me how how I can skip the grind (that is tuned to irritate me) by buying a gems with my credit card.
I'm not as valuable to Blizzard/Activision/NetEase with my one-time-purchase though, and they know it.