People chose to care, and you define a like in the terms you've stated. But Instagram makes no such claims, neither about the nature of the likes, nor restricts particularly how they can be created.
If anything, the example you give example supports the notion that "fake" likes are just as good as real likes, since pretending to be a celebrity can in fact make you famous.
It seems needlessly obtuse to say that Instagram have never stated that a "like" represents someone liking your photo. That's the reason they called it a "like". If you want to make the argument that Instagram chose a name for something without wanting to attach any meaning to it then good luck to you, but it's not a conversation I'm interested in having.
> nor restricts particularly how they can be created.
Untrue, given that they've cracked down on bots posting automated activity on Instagram:
If anything, the example you give example supports the notion that "fake" likes are just as good as real likes, since pretending to be a celebrity can in fact make you famous.