It's certainly not impossible, but requiring a donor putting up significant amounts of money in perpetuity is not "easy". There are not a lot of people in the world who can just drop $1.5M every year on what is essentially a passion project, there are even fewer who want that project to be college sports, and even fewer than that who love college hockey and not football or basketball.
Even with this gift, the amount of money they have to play with is not actually that much. Probably half of it at most will be given directly to players. You have at least 20 guys that you probably want to spread that money around to. Not that ~$30k isn't real money, but it's probably not enough to convince top end, NHL prospects to come to your school especially when your school is not very prestigious hockey-wise or academically.
It's not that NIL doesn't exist for hockey it's that
1) the sums of money being talked about are much lower than you'd think
2) at the flagship programs, football is the all-consuming black hole that is every booster/collective/AD's first and last priority
3) foreign players for the most part cannot make any NIL money while on a student visa