This is not to say that this entitles anyone to do so without Apple’s consent, but the argument about resource usage is a straw man here, IMO. This is not about who pays for the servers. Even if Beeper would offer Apple an appropriate portion of their revenue (edit: and they actually do in TFA), Apple would not agree. For Apple, this is about keeping the garden wall up.
On iMessage, all messages are stored on Apple’s servers (at least in-transit), even those that would be destined between two Android users communicating via iMessage.
At least with email it’s a bit easier to filter out spam, but iMessage is also E2E encrypted so automatic spam detection is much harder.
Which is the intent of running those email servers. These are the “public-use” servers. The iMessage servers are private.
There are much better business arguments to make here then "oh no! The 3 trillion dollar company might have slightly more overhead managing text messaging!"
From a business perspective, I'm much more sympathetic to arguments that iMessage is a perk Apple wants to keep as incentive for more users to switch to Apple's ecosystem and, likely more important, lack of cross-platform interoperability raises the cost for existing Apple users to transition to Android.
Are you claiming Apple would have to pay fixed costs a second time because new users were added to the already existing service?
And are you claiming that 1 million dollars is a lot of money to Apple, a company worth over three million million dollars?
I was responding to someone who said the extra overhead for running a chat service that has more people use it would be notable for Apple. A business argument - not a legal one.
No 3rd party batteries in devices or 3rd party ink cartridges either
That's about the strength of it. Unless the protocol is open, paid or otherwise. iMessage is closed and undocumented.
I'm willing to buy all of your property for $1, but that doesn't give me the right to come use it all, just because in theory there is a price I would pay to have it all.