Coin Mixers are really helpful in making transactions hard to track or untraceable at all
I don't think it's untraceable, as long as everything goes through the blockchain, everything can be trace, but with mixers, it will make it harder.
Mixers are most helpful for people who like to launder their money to get out clean going to their exchange but I believe more users are using it legally.
but it is giving some scammers an advantage they are using it to anonymize their transaction and exit freely which is not good for the crypto community, even though it is very useful if you are concern about your privacy it is a good alternative for privacy coins.
It's another advantage because mixers are also being abuse by criminals, so I don't know if mixers will last longer as crypto is more popular now and the eyes of the regulators are already looking unto us.
Read this op,
Cryptocurrency Mixers and Why Governments May Want to Shut Them Down