I understand your opinion.
But a username is still superior compared to an email (especially since emails can be used to contact and phish you with). Whereas a random username is just that a username and no way to contact it via email and no way to know it. Unless the service is breached and you tell someone.
Therefore a username that is in-fact totally random and not related to any personal facts about the user or their email is by far more private than an email. As it can be changed easily and monitored efficiently.
And to your point about anonymous email services. I am not personally going to use some anonymous email service to use for one account. Especially if it needs to be a paid or free like DuckDuckGo. I am going to stick to my public email like every other ordinary individual that uses the internet and is not overly paranoid about having to have separate emails for each account (and yes you do not need to be paranoid to use anonymous email services, there are security advantages, which I understand. But not everyone needs them if they practice good cybersecurity hygiene like using a password manager to create strong unique passwords on every site etc)…
That is where a username solves that issue of a user using one email for security. Especially if the user likes to keep a watchful eye on data breaches. As usually keeping one email is better for the user to get to know exactly what data got exposed from what service and it is also easier to track. Also using one email is better for data removal services.
If a user is using separate anonymous email aliases for each site they will not know of certain information being breached especially if they deleted that email long ago along with the account as they will not have access to it and if the user never kept note about it for that service. So the user would not know how to take action for that data being exposed. Since hence the account being deleted or alias.
So, how would they know if the service still had their information etc. As deleting an alias email would leave it impossible to ever receive an email about the data breach. Especially also if they deleted the account as maybe 10 years down the road. If they decide they may not need the disabled email anymore. The user then decides to delete it. But then the company gets breached and surprise their data was in that breach, even though it was 10 years and they thought since their account was deleted the data had been too since it past the amount of time in the privacy policy. That is why personally I believe a user should always use just one email.
So, maybe some people prefer that method. But it is expensive and unnecessary/time consuming to keep track of. As these anonymous email services usually get you banned or your account suspended and then you have to submit a personal request to get it reinstated (cough, cough, EA and GitHub etc)(Personal Experience).
So, that is just my opinion and personal experience. If you like to go that route that is fine and you are all but able to. Hope this didn’t come off as rude as I am just trying to state my opinion. As aliases are just not for me.
Sorry for the rant I didn’t know how to explain it any other way.
I do thank you for the Gmail alias information. Didn’t know that was possible. Still won’t sway me to use aliases though as it is just not my thing.
But I do thank you for the discussion.