Re: I've seen a definite uptick in these
Yahoo does have a similar feature, although you have to create a myprefix-<throwaway>@yahoo.com mailbox before you can use it, rather than Gmail's instant madeup-on-the-spot address.
Yahoo's advantage (Yes, there is one...) is that if you get spam to that mailbox, delete it and you get no more.
Other mailboxes are available
P~