It's not just about the history of them but also where they end up, and on bitcoin all coins end up in the UTXO set, which is what enables us to know "rich wallets", top holders, spending habits, and so on, on Monero not only the "utxos" have no immediate history like you say, you also can't tell where they end up, and if they are unspent or already spent, hence why they are not "u"-txos in Monero, those outputs show up multiple times through the blockchain's history but they could be standing still not moving at all. So hence why I said the only metric we have for XMR is the tx count, surely some attacks can be perfomed to trace specific senders but not how many users are there in XMR, how much is being held, who is holding the most, and so forth