Well, there's not much difference. That's usually the problem with all hard numbers, even on much more important issues like becoming a legal adult. I don't like this cutoff date particularly either, to tell you the truth. But it's a quick and dirty system.
One way to fix this might be to drop players from prospect status if they don't play enough games due to injuries but you open up a can of worms because at one point, you risk encountering prospects where it isn't clear whether they would have stayed with the team or not without the injury. And it adds more work.
So I guess we're back to a fixed cutoff date. Now, you have to look at a number that is satisfying. Nobody is going to agree on the hard number. Would 11 games be it? That would filter prospects who get the 10 game tryout (without the contract kicking in) but never had a chance to stay up. Or we could go the other way and say a full NHL season of 82 games? Less? More?
I don't know, but whatever number you choose, there will always be a guy who *barely* played too much or too little and it will always make no sense. Just like it makes no sense that you can't drink alcohol one day and the next you can get ****faced for your 18th (or 21st) birthday.
I agree with you that the system is flawed but I don't think you can really fix it to make total sense in all situations. Or rather you could with a page of rules and guidelines that overcomplicate the process.
Because of the champagne and the ring, of course