No idea, just pointing out it is such an obvious alg it doesn't really show provenance.
I used similar (well, plus addressing with localpart=name+<service>) a long time ago and once got emails to name+paypal@example.com even though that was a suffix I'd never used. Some enterprising person out there had obviously obtained one or more of my service-specific addresses and was trying to game my attention by changing the identifier to something 'important'. That's when I personally ditched the approach.
"Provenance" might be have been a bit too strong; maybe I should have said "strong signal". It's an additional piece of info that will almost always identify the source, but in the rare exceptions it's not any worse than if I just used a single address for anything.
I used similar (well, plus addressing with localpart=name+<service>) a long time ago and once got emails to name+paypal@example.com even though that was a suffix I'd never used. Some enterprising person out there had obviously obtained one or more of my service-specific addresses and was trying to game my attention by changing the identifier to something 'important'. That's when I personally ditched the approach.