Arrival : Why does just Louise see the future?

After seeing the written heptapod language the first time Louise starts perceiving time in a non-linear way in small glimpses and sometimes sees the future. The movie explains how this happens because she can speak heptapod in the future and you shows you the future where she is teaching heptapod to a school class and the movie hints about future earth united with one global heptapod language.

But if everyone in the future knows heptapod why is Louise the only one that starts perceiving time differently? Wouldnt everyone that sees the language see the future and understand what to do instantly? Even if the director (maybe) tries to make it look like the tragedy of her daughters death somehow acted as a catalyst to make her learn the language faster there's atleast a few million other people on earth that's going to experience enormous tragedy after learning heptapod in the future and thus having a "catalyst" aswell.

Did I miss something?

It's not because she can read heptapod in the future, but because she can read it now. She's the first. I think Chinese general or some of his men can understand time too. Beyond that, I doubt many people on Earth would ever be able to understand it. After all you can't speak it.