The disagreement is about who determines what is spam. One group thinks it should be the miners deciding the block sizes they produce and the fees they require for admission. The other group thinks it should be an insular group of friends on irc, with a blatant COI.
Free market deciding or group of elitists deciding... strange there is still support from part of the Bitcoiners that elitists decide better, which is basically the same how the old financial system is governed.
Just the last excuse is full nodes might not keep with bandwith, CPU and storage requirement when miners are free to decide about block sizes. But miners act rationally to keep the coins+fees worth something in at least short future as well, thus the doom scenarios about full node centralization is myth because it is not in miner interests to have small price of Bitcoin as a result of continued distrust in Bitcoin.
Give faith in free market, and you will get the most efective system ever possible. No human regulators can come even close.