Someone needs to be the first to push it. In this case, Apple is probably the #1 or #2 generator of photographs on the planet, and it's a lot easier to make something happen quickly when the format is supported in that way.
HEIC is heavily patented. If it was apple's intent to push a new image format for everyone, they chose just about the worst one. It's much more likely they decided to trade off interoperability for lock-in and reduced file size.
