We're off to a pretty good start but man was I getting a prequels Anakin vibe for a good bit there with Ezra. I mean it's fitting given what he's been dabbling in but that's some tilled earth I don't like going back over again.
They weren't invited because they didn't exist conceptually. Their overall story arc is forced to lead to someplace other than they being prominent figures in The Rebellion by the time Ben becomes directly involved.
But Rex does make it through to the Battle of Endor in RotJ (via retcon).
I think this is heading to Kannan and Ezra becoming Grey Jedi or "Jedi - Bendu." In which case they could technically not be considered Jedi by Yoda anymore when he does his stuff with Luke.
good to see that Thrawn is being written as a man who plays the long game.
I really do see a broader focus from this and the new series of movies on Balance within the Force as the Jedi and Sith are just too extreme and polarized to be healthy