Earlier quoted context omitted.
The emoji is consistent across their system. That’s the consistency that matters to most users.
Incorrect, because emoji are being used to communicate with other people on different systems. That's their primary purpose, not to write to yourself.
It is consistent for the user on whatever system they are on. If they switch between apps, they see the same emoji that they’re familiar with.
The web developer doesn’t have to care what the icon looks like. They just say: use this emoji that semantically means “flower”. They know it may look different to other users but it will look like what that individual user is familiar with.