A few other things to consider.
One thing I’ve heard from players before is that when you take the NCAA route to get your education and play, you’re doing so on a high. There’s such great optimism about your career and you’re going with the intention of being a pro hockey player, but also getting a great “back up plan.” Where as when you are using your CHL education package and playing CIS it’s more of a “fall back plan” in the sense that you’re now going to school as someone who failed to make it as a pro player after your CHL career didn’t secure you a pro career. Not saying I agree with that mindset. The CIS is better hockey than it gets credit for and tons of players become pro’s around the world after. However I do understand the mindset because it does significantly decrease your odds of being an NHL player.
The other thing is just that the window for NHL attraction is so much larger. Some agents and advisors are pushing the NCAA route because even if you’re not drafted, you’re going to school and NHL eyes will be on you for a large period of time. Basically you're being heavily scouted from 17-24. Allows for improvement and maturation, which is non linear and different for every person. Let me give you an example to back up what some agents are suggesting. We'll call them Player A. Player A is a highly touted young hockey player that goes to the NCAA route. He signs an NCAA scholarship agreement early and plays in the USHL. However, he struggles with the adjustment and is a USHL role player for two years. Not on the NHL radar. But as a 20 year old in the USHL, he finally plays better. Not an elite level, but much improved. Still not drafted, but he's going to a great school and is going to make this adjustment with a ton of confidence. At the NCAA level, he improves every year and ends up signing an NHL deal after his junior year at 23. Now...let's look at what happens with Player A if they take the CHL route. They struggle with the adjustment to the OHL and are limited to being a role player early on. That probably means they end up being moved to another team for a fresh start by their 19 year old season. If they're still struggling, they may not even have a place in the league as a 20 year old (OA). Then it's the OJHL and to the CIS to use your education package. Maybe that's when he's physically mature enough to be at his best, but he didn't attract a bigger CIS school because he wasn't a former CHL standout. That means his attention from the NHL is nearly non existent.
The last thing to mention here has already been touched on. Players going the NCAA route have so much more autonomy. The Transfer Portal has been a game changer for that. You don't like the school or coach you picked first? Change teams and you get to hand pick the new school you want to attend. Heck, you could even decide to go the CHL route after all, if you regret your choice...like Justin Ertel recently, who signed with Dallas recently.
Look, as someone who has covered the OHL for decades, it definitely hurts to see so many high end kids leaving the last few years. However, I do completely understand why they are.