A bit of a late reply, but there were a couple of points that I wanted to respond to. The first is that I'm not holding up WhatsApp as a great example! I use, p

A bit of a late reply, but there were a couple of points that I wanted to respond to. The first is that I'm not holding up WhatsApp as a great example! I use, promote, and have done a bit of development on Matrix, a true open messaging system. If XMPP or IRC floats your boat, I'm all for that as well, and I'll be able to chat with you over the XMPP and IRC Matrix bridges because all 3 are open systems. Second is how high the wall of your walled garden is matters, and matters a lot. Sure I can't write my own WhatsApp client, but I can download the app relatively easily on both Android and iOS. To communicate with people over iMessage I would have to buy a different phone and accept everything that comes with it (including the rest of the walled garden, appwise, oswise, etc). Finally, when I said they were doing it for profit I meant that the fact that iMessage only works with Apple products makes it such that if you want a good communication experience with your Apple-only friends you also have to buy into the ecosystem, and once you have it's hard to get out because you might lose those connections.