Every "new use case" bloats UTXO set. OP_RETURN opens up possibility for virtually unlimited, arbitrary nEw UsE cAsEs on Bitcoin.
Restrict the consensus rules so that so-called "OP_RETURN" arbitrary data is disallowed in order to curb bloating of the UTXO set.
Besides, use "datacarrier=0" option in Bitcoin Knots. It blocks the spam from propagation in P2P network mempools and so denies it anonymity.