You're right, it is a practical protocol choice... One that I think does have arguable impacts on decentralization.

This is similar to the "blocksize wars". The argument for decentralization was that, if you increase the block sizes too much, it will be too costly in terms of computation to run a full node.

There's something similar there in comparing (say) SSB or ATProto to Nostr. The former systems require you to update the entire state of the system, and keep it live-updated, to be able to participate in the network. This, in my understanding, is a big reason why ATProto isn't more decentralized.

As for the experience of legacy social, say X users, as I've argued both the "permanence" and "deletability" of posts on those platforms are sort of illusions. Do X users really trust that some tweet they made 5 years ago is still on the platform? Conversely, does Kanye really think that when he deleted all his tweets, nobody's archived or backed them up? Of course not....