This mixer of a thing help people dey anonymous.
If your transaction is known and tracked but using Tor with it and not linked to your real identity, that is anonymity. But if you send the coin that is tracked to a mixer like Whirlwind and you mix it, that is no more anonymity as you want to achieve privacy. That is privacy. Mixers are used for privacy reasons.
As technology don improve, e dey possible to track Bitcoin transaction back to where e don start with their IP.
You can always use Tor instead of using IP address directly to connect to your noncustodial wallets. You can do that on computer. Orbot makes that possible on phone. But mixers are still very important to achieve privacy.
Tor for anonymity.
Mixers for privacy.
As e get good side na so e still get small disadvantage, them don associate the mixer stuff with money laundry and some other illegal act.
Let us take Boko Haram and bandits in Nigeria as examples. What are they using for survival? Is it not Naira and fiat in general? Another example are the people in public offices. What are they using for embezzlement? Is it not banks. Another example. Is naira not connected to money laundering? Money laundered are mixed with legit money, using legit businesses to make the public not to know. Fiat is more used for online criminal activities.
If some people use mixers for bad activities, it is what is related to money. There is nothing related to money that bad actors will not get involved. It is also worth knowing that mixers are not a disadvantage for good users. You used a reputed mixer and you will not be scammed. That is not a disadvantage because it helps people's privacy.