Just because you believe the FB/G nonsense that the internet is only possible by gross violations of user privacy doesn't mean everyone else buys into it.
They don't need to record what app or service got the alias address, and they explicitly state that they do not record any details about interaction with your service, or any emails that go through the alias. It's an explicit statement in the linked talk.
Which accounts doing what?
Businesses sending to a cloaked email?
I'm not trying to say this is a bad thing, I love what apple's doing here. I'm just trying to push back against any suggestions that apple is giving something up. They are collecting more data about their users now than they were previously, and positioning themselves as the gatekeeper of user identity. There's every indication that they're doing this for the right reasons, and it's good for users, but it still increases their control and their stored user data.
On the other hand, Apple is tightening its control over its own ecosystems as every interaction has to go through them. Moreover, they're inhibiting anonymous usage of services as more and more things required direct or indirect verification of the user. This entices the market to normalize the demand for unique virtual identities.