Well, this is all 100% true. Us Monero dudes often say "this is a known issue and we are taught never to re use subaddresses" and while that's true, they're deterministically generated from our private key and so cannot be deleted, and it is taken for granted that we will reuse them so much that it is encoded in our UX for basically every client. Still, I would say that as a privacy shortcoming, this is the least detrimental one to have, but youre right, that doesnt mean it doesnt need a solution.

You might find this interesting, in MW, transactions are sent side channel and must be signed by both parties. This works like an ephemeral record of who is paid, all the sender has is an email address or something that they do not have to keep indefinitely, like option A above. The signatures are schnorr signatures and so what gets written to the chain is a combined signature that nobody but the parties to it can tell they were parties to it. And, ultimately the only thing that is needed for consensus is the UTXO set, so once the recipient spends the output it is no longer kept as a record, in contrast to literally all other blockchain protocols. The shortcoming with it is that this deleting of old transactions cannot be forced on all nodes, so while those transactions are not needed for consensus, a node choosing to keep them anyway can probabilistically put together a graph of counterparties from them over time. This is actual tracing by third parties and so the trade off here is not worth it privacy wise.