If I remember correctly the founder of TenX said in a video that 40% of all Fiat <-> Crypto money goes through Coinbase alone...which ties (a lot of) future transactions to a passport verified person.
Even that doesn't really tell you who the real owner of the coins is. What if you bought bitcoins for your friend and withdrew to his address? Or you got hacked, or blackmailed, or ransomwared.
Not if you also have a local wallet and transact with non centralized entities (ie other people) often.