Pointing out his shortcomings is hardly "eating their young". Back in the 2015 Finals people thought Joe Harris should have gotten more time due to injuries. Arguing he wasn't ready didn't mean he wasn't a player with potential, it was a statement about where he was in his development at the time. I'm glad he is realizing his potential this year, but it is happening in the right situation for him: Big minutes on a team with no pretenses for contending.
Back in the 2016 NBA Finals when the Cavs were down 3-1, numerous posters were clamoring for Jordan McCrae to get minutes in the rotation. Would it have been "eating our young" to suggest he isn't ready to be in the rotation of a Finals series over other players? No, it's simply stating reality of his progress thus far.
So, let's keep conversation about rookies in the proper perspective without hyperbole. It's okay to look at areas for improvement in young players.