In a spam attack when someone is pushing garbage into the blockchain (as it is a "freedom protocol") the fee market kicks in and increases the cost for them.
The Bitcoin blockchain doesn't recognize incentives and types of spam attacks in this matter. Nor do humans know with 100% certainty. There is spam, and whether it is used to fulfill the owners of some shitcoin or not, the same damage is done. If the Bitcoin network allows for specific types of transactions, then idiots who push their shitcoins are also welcomed to broadcast their transactions if they're okay with the rules.
Sure, the blockchain doesn't care, but in a maximally free situation, the NFT people would 'win' in the sense that it may only be worth paying high transaction fees (due to high demand for these JPEGs) to send around those expensive NFTs or large Bitcoin transactions. It may not be worth it / profitable to use Bitcoin as an everyday currency anymore.
Don't estimate the NFT market; while we think it is ludicrous and stupid, there is a lot of money in it. Money that may make the Bitcoin blockchain unusable in favor of becoming a platform for JPEGs.
So I do understand both sides, but lean towards the 'keep it payment-related' side. We already have payment networks
on Bitcoin that are easier and more scalable to extend (e.g. for adding JPEGs).