How could a person link the transactions, they can only see that they came from Coinbase but cannot see which of the millions of Coinbase users sent it and cannot see that these transactions came from the same user. Am I wrong about this?
Are you aware that what you withdraw/send from centralized exchanges is the coins you or others have sent?
If you deposit and then withdraw, there's even a chance that the withdrawal will be from your deposit address.
Since Coinbase is not a mixer, sending to the various customers have a good chance to link them.
This is how I see it.