Of course not, but they're 99.99% of the way to letting me use them to sign up for potentially spammy registrations, and for me they need to go 0.01% of the way further. Since I use it for so much important communications, I really am not budging on this, and will continue to use mailinator for throwaway registrations until they stop requiring me to send my base email address in plaintext to potential spammers.

Another potential issue is that someone might not necessarily want to associate these registrations with the same user. For example, after the Ashley Madison database was compromised, the intersection between those users and the users who are millionaires and billionaires could be quite valuable to criminals, or, for example some lawyer or something. (For extortion.)

If the base email address is included, that intersection is easier to find, via compromise of other email sources. The current solution is just not secure enough to be used, and I don't use it. But I like it, and it's 99.99% of the way there.