Your example doesn't seem valid. Instead of:
stuff.alias.user@spamgourmet.com.example
You probably meant:
stuff.number.alias@spamgourmet.com (you can't append anything past the TLD).
I didn't vote because I don't see the need, nor do I mind if they do implement this. IMO, development resources should be invested elsewhere (e.g.
here)
Prog.