So the GP volunteers unasked for feedback and that's cool. I do the exact same thing they did and somehow that makes me the asshole?

I already covered the fact that tracking problems can be due to reasons other than poor eyesight. I even provided supporting links for that assertion.

Part of my background is working for an educational organization that catered to the needs of gifted kids, including twice exceptional kids. It was common for early readers to have tracking problems and for parents to share practical tips on how to cope, as well as talk about at what point to get concerned and get the kids checked for something else.