Doesn't even have to be long-shot prospects. Just non-elite guys. Your second round picks and on. Even first round picks who maybe have a lot of skill but whose games are very raw.If for no other reason that teams get to own the player's rights for 4-5 years, NCAA is indeed a much better path for long-shot prospects.
NCAA, you get to practice a lot. You get to play against players that are much more developed physically (on average) and who have years of experience on you. The level of play has really improved, the amount of quality teams and players has really improved. It's a great option for any player, really, which is why you even see more European guys coming over to play in the NCAA--it basically tripled in five years. More Canadian kids are coming.
The really elite guys, playing in the CHL is fine as they can just go do their thing and score 10000 points for a couple years and then join the NHL squad.