If something bad has 'been done before', do you think it is a really good justification to keep doing it?
You missed my point. What i wanted to emphasize was Ordinal isn't necessary to do that. And obviously, people should stop doing it.
Bitcoin should be good at one thing and one thing only.
I agree. But on technical level it's impossible to ensure Bitcoin only can be used as currency/payment method while remain decentralized/permissionless.
Why is that impossible? Look at Monero, for instance. Or other privacy coins. Since they hide most information, you kind of get 'payments only' as a side effect. 'Modern' cryptography still allows you to verify transactions before mining them / adding them to your node, without knowing everything about them.
Well, can you think ways to completely prevent people from arbitrary data on Bitcoin blockchain without taking away decentralization? Before Taproot and OP_RETURN exist, people already can do that by either coinbase transaction (limited to miner) or using legacy Bitcoin address by abusing 20 bytes which supposed to represent hashed public key.