You're implying that mixers and tumblers are ONLY dedicated malicious services.
What you're forgetting is that hot wallets used on popular bitcoin services also serve as tumblers. The distinction between a "malicious tumbler" and a service's hot wallet is just the dedicated use.
For example, if a bitcoin shopping site had a wallet you deposited coins into, you'll be recording that you have <number> of coins and they will show that. Your coins will be mixed with their hot wallet and who knows how long they keep them in there.
If you wait a few days and withdraw, chances are that most (if any) are NOT your original coins.
Not to mention, if you blacklisted these coins, then users who receive these coins wouldn't be able to legitimately use them.
TL;DR: Tumbling services are just dedicated to tumbling bitcoins. Most semi-large bitcoin services with hot wallets inadvertently tumble their user's bitcoins.
What you're forgetting is that hot wallets used on popular bitcoin services also serve as tumblers. The distinction between a "malicious tumbler" and a service's hot wallet is just the dedicated use.
For example, if a bitcoin shopping site had a wallet you deposited coins into, you'll be recording that you have <number> of coins and they will show that. Your coins will be mixed with their hot wallet and who knows how long they keep them in there.
If you wait a few days and withdraw, chances are that most (if any) are NOT your original coins.
Not to mention, if you blacklisted these coins, then users who receive these coins wouldn't be able to legitimately use them.
TL;DR: Tumbling services are just dedicated to tumbling bitcoins. Most semi-large bitcoin services with hot wallets inadvertently tumble their user's bitcoins.