Importantly, if "Warren Buffet comes along and wants to spam our network" his bad actions would be tied to addresses that can be blacklisted. You can't do that

Importantly, if "Warren Buffet comes along and wants to spam our network" his bad actions would be tied to addresses that can be blacklisted. You can't do that with PoW without "additional" consensus rules, which is that slippery slope to PoS!