So I thought iMessages addressed to a phone number should only go to your iPhone (and not your iPad or Mac, let alone your Apple Watch (which was years away from being released) or glasses (which remain years away now)), and Phillips thought iMessages should go to every device, but should only use phone numbers as identifiers. I’ll score this as me being very wrong, and Phillips being a little wrong.
2012 was a long time ago, and I think this is a good example of how the world has shifted in the past decade. This distinction between your phone and computer is not something that makes much sense in 2020, but I totally get how that was a thing back then.
Today, the expectation across basically everything we use is that I can do something on one device and pick it up later on another device, and it doesn't matter if I use a phone, a tablet, a desktop PC, or even my watch, the experience should continue across all of them. The idea of my messages app having some messages on my phone and other ones on my iPad or Mac is crazy to me, but agian, this wasn't as crazy an idea a decade ago.