Because if the entity you call "the wallet" actually mixes their users' outputs well, then who are you to tell everyone that "there's no underlying purpose for its existence"? If it's a service and does the service well, then it's up to you to use it, or not to use it.
The entity's wallet doesn't mix users' outputs at all. There's absolutely nothing technological involved here that enhances privacy.
I'm talking about a hypothetical mixing service that actually does everything right, which may also exist somewhere, no?
But if you believe that a mixer that was advertised in BitcoinTalk is/was merely an "entity's wallet" that does/did absolutely nothing, then please ser, kindly show us the data/proof of your findings.
That would stop the nit-picking in the topic.