you cannot stop spam pubkeys…and those show up in the utxo and cannot be pruned you are incentivizing centralization as ram requirements push minimal hardware setups off the network. The purpose of the op_return is to prevent utxo bloat.
I would rather upgrade my hard drive to handle some stupid monkey jpeg(or run a pruned node) than upgrade my whole machine because you wanted purity. You would rather virtue signal.
Do you see it now? The ram requirements are already making node hardware options more expensive.