Well, the athlete can commit to the offer and then if something goes bad (injury or sucks in high school), then the school can always pull the offer and the player can complain about no loyalty.
The player could commit and then de-commit right before signing day and the coaches can complain about no loyalty.
Not a whole lot different from handing out offers to juniors and seniors since both sides can change their mind any time before they are signed.
As a coach, you want to get in early on a kid to increase your chances of getting him to commit, but at what point do you look like a fool when the player tops out in junior high and isn't even worthy of an FCS offer?
I had a kid in my class that was 6' 1" and had to shave every day when we were in the 7th grade and he never grew any taller and he looked the same as a senior as he did in 7th grade. Everyone thought he was going to be great, but everyone passed him up by the 10th grade and he was nothing special after that.
Remember David Sills? Lane Kiffin offered him in 2010 when he was a 7th grader I believe and he eventually committed and enrolled at West Virginia.
He was a 4-star and rated the 15th pro-style QB by the time he signed. I would say Kiffin happened to get that one right, but you never know when someone will peak.
Sometimes it's better to get those late bloomers that no one notices until their senior year and then they are still getting better in college.