Aliases you can discard are ad blockers for emails, disposable services are for bots, scams, and fraud. If you know the space, you'll be aware CAPTCHAs are trivially defeated today, regardless of the provider.
I certainly agree people shouldn't be asked to provide an email if it's unnecessary, but again for the issue of bots, scams, and fraud, you generally need some sort of unique relatively hard to get many of identifier to prevent people making tons of accounts on any service which either allows posting content or costs money to provide service. Email is generally okay for this.
Ultimately disposable email providers who continue to believe domain rotation is anything but an attack will force a far worse outcome, which I've already seen some major sites do: Only accept registration from Gmail, Outlook, and Yahoo accounts. (The Verge is one example where I know I had to register with a Gmail account and open a support ticket to change my email to my real email because they figured out the best way to avoid abusers on disposable email was to allowlist major providers.)
I certainly agree people shouldn't be asked to provide an email if it's unnecessary, but again for the issue of bots, scams, and fraud, you generally need some sort of unique relatively hard to get many of identifier to prevent people making tons of accounts on any service which either allows posting content or costs money to provide service. Email is generally okay for this.
Ultimately disposable email providers who continue to believe domain rotation is anything but an attack will force a far worse outcome, which I've already seen some major sites do: Only accept registration from Gmail, Outlook, and Yahoo accounts. (The Verge is one example where I know I had to register with a Gmail account and open a support ticket to change my email to my real email because they figured out the best way to avoid abusers on disposable email was to allowlist major providers.)