I use them for different purposes. They are "role accounts" for projects I am doing, such as geneaology and astronomy.

In order to use YouTube sanely, and store different stuff in Drive, I separate them into unique accounts. I use those accounts for specific things, and my YouTube subscriptions, playlists, etc. are tailored for each role, for example.

This is not about email at all. Obviously, I can access all those email accounts through the one app on my smartphone or the one PWA on my Chromebook. They are easily manageable but separate.

I also run 3 Outlook/Microsoft accounts, and for the same reason. (One of them is my academic account from community college, and the other two are personal.)

I don't need to give out email addresses for the "role accounts" except where I "Sign In With Google" to various services. So I don't really send/receive email from them at all, except where I'm sharing links or documents with myself (the best way to do this cross-account is still by using email, oftentimes.)

In fact, this is plainly evident by the way they give you tools to operate them in a systematic way. You can add multiple accounts to a single Android "user". You can add them to a single Google Chromebook account under one signed-in account. You can add multiple accounts separately to the same Chromebook.

You can add multiple accounts with the same names, the same birthdates, and the same Driver License. I've validated at least two YouTube channels by showing exactly the same ID.

Google did not terminate your account for the reason you state. You are not telling us all the background information.

Google may indeed terminate multiple accounts for the same person because of TOS violations. They will definitely link and associate your accounts, so making an "alt account" for misbehavior is not safe. If my "alt account" is compromised or violates TOS, then I can expect they will discipline all 6 equally, because they're all linked.

But operating multiple accounts is very explicitly supported by Google, and by Microsoft as well, I will say. I don't know about Apple. Facebook definitely prohibited this in the past, although you can maintain multiple "profiles" and "pages" that have unique settings and personalities.

Of course, with a well-known email address, you could run a higher risk of credential stuffing, and an account takeover by someone who hijacks your email account, and then pivots from there to taking other accounts.

But this seems to be a risk we all take: email addresses are meant to be shared, to be public, and to be well-known to anyone to correspond with us.

I will say that disclosing my email address to certain parties has had noticeable effects. For example, I used "MYADDRESS+Echovita@gmail.com" once, and only once. My godfather had passed away, and I ordered some flowers for his funeral. And I put that order through with that email address.

Well, Echovita themselves had a data breach shortly afterwards, and I was inundated with scam emails. Just all sorts of attackers and they were basically all using the same M.O. But they were readily identifiable because I had used that "+Echovita" to identify it uniquely. And they really haven't stopped coming in. It's been 5 years since that breach.

So yes, especially with untrusted parties, it may help to tag your email address. I don't worry about receiving spam anywhere. But like I said, since I've never ever disclosed the addresses of 2-3 of my "alt accounts" they simply never receive any mail at all, spam or no spam.

For spam which only does not require manual effort on the other side, there is no reason to filter out potential victims and all the more reason to make it look as legit as possible to maximize conversion rates.