Wasn;t there a day where zcash had only 2 transactions total? these anon coins suffer from their very small user-base.
Though, if there are only a few transactions each day that's not as large of an issue as it sounds; the blockchain still has no linkability between transactions. Active attacks might work but few attackers can pull those off, and no attacker is able to go back in time to deanonymize older transactions (assuming the cryptography holds).