Let me try to make my point once more:
1) Address reuse is actively harmful for the whole Bitcoin network.
2) On-chain privacy is very, very hard.
3) Lightning privacy is NOT hard
What (3) means is that I can spend the zaps that I have received WITHOUT getting into trouble further. I can spend them at a merchant or whatever, and nobody will know. On-chain makes that way, way, way harder. On-chain is traceable.
Further, nobody knows the current balance of my wallet. I might have spent everything. Or maybe I haven’t touched it. Switching to on-chain makes every user naked, and thus plausible deniability flies out the window.