Yep, the idea is to have some kind of filter that people agree on.

For example: I own one of all the utxos that were created between block 750000 and 800000, and whose size is at least 0.1 btc. That number is probably not too large, and doing it this way you can get big anonymity sets without too much inconvenience to anyone.

It is pretty tricky practically, but it is clearly possible.