They are not "misleading" when you know what they are based on.
And that is the problem - as some brands cover "the full range" in a wind chart, meaning they put the windrange for a specific kite, but for both light and heavy riders, and big and small boards.
Which gives a huge windrange then.
Others go the other way, and specify a given weight and board size, and not too over nor underpowered.
That will give a really low windrange then.
So if you know exactly what the ranges are based on, you might be able to compare a bit better yourself.
But as a starting point - I would never ever use wind range graphs at all, because of above
If you had some kind of a standard measuring method that could be used in terms of windrange - THAT is what I would like to see (but I dont think this will ever happen).
The problem is, that "new" kitesurfers take these ranges for "GIVEN", and sometimes choose from these
So some will buy a 7m2 and a 15m2 kite as their full quiver, as the ranges "overlap" according to the charts
And we all know this just wont work at all