Ancient mistypes of email addresses carried some mild risk.
User would mistype their email address, inadvertently entering a valid (but not their) email address.
The webmaster would send a confirmation email to that address. Stupid webmasters skipped the confirmation step and just sent to that address.
The person getting the email would report those emails as spam. Sometimes their reports would be effective and block email delivery for a while.
Someone ages ago had a nice website talking about this. They had a domain that often got email for other people from mistyped domain names.
Obviously allowing users to copy paste the email address is sub-optimal.
What's the better flow today? Send a confirmation email and allow the user to correct the address if they don't get the email?