I'll disagree here.
I think it really depends on the player that you're talking about and the situation at hand.
Zegras is a player who is certainly not lacking in confidence; he has it in spades. If he struggles with consistency and if the Ducks aren't winning, I don't think that's going to shatter that confidence.
If the AHL was actually having a playoffs, I might agree with you. I think back to what Philadelphia did with Mike Richards and Jeff Carter many years ago, getting them in a deep playoff run in the AHL following the conclusion of their OHL seasons. It was massive for their development. But without that opportunity to play playoff hockey, is Zegras really going to benefit from putting up gaudy numbers in the AHL against, quite frankly, many watered down rosters (due to taxi squads)?
Zegras is a kid who has won at every stage of his career and has always been a part of winning teams. Be it the USDP program. BU. The World Juniors this year. Maybe the best thing for his development is to face some adversity and to see how he copes with it? Let him learn to play through traffic at the NHL level. Let him figure out how to be more defensively responsible. Let him continue to work his magic on the powerplay. If consistency isn't there, who cares? It would then give him a chance to see what he needs to work on next offseason so that he can come back even better. Quite frankly, I'm not sure that the AHL would give him that sort of feedback at this point.