Same here. I presume that one day I will have to write something using a GAT, and then the understanding will click with me, even if I don't speak the terminology.
Both generics and traits are mostly for library authors trying to make expressive APIs. If you're not creating libraries but instead consuming libraries, then it may be natural for you to never need to reach for this feature.
Many C++ developers have walked that path, never to be seen again.