Assume you have a utxo, and want to spend it privately.

If you do only single user transactions, you would need probably 50 transactions, creating 200 coins, and spending 180 of them, that's a lot of blockspace, and you didn't create much ambiguity of where the und money went.

On the other hand, with WabiSabi it might give you sufficient privacy to make 1 single transaction, spending 1 coin and creating 5 coins. That's a lot less blockspace.