Why not? But you certainly don't have to trust me on that: it's what actually happened. Apple added support for Softbank (unicode-based) emoji when they started working on japan, and non-japanese started using that even though it only worked between iOS devices[0] (didn't even work on OSX IIRC). Hell iOS has its own proprietary messaging system and people use that.

[0] it actually required "unlocking" the relevant keyboard by starting an application which used those characters or something like that, shit was crazy, it took several ios versions for apple to make the emoji keyboard available to any and all OOTB