I guess in this case I'm using the term 'account' and 'magic band account' interchangeably as nothing is actually loaded onto a magic band, per se. I mean, obviously, your credit or gift card isn't swiped onto your physical band. The charging mechanism (having something on your person that communicates with stored payment methods) hasn't changed, just the physical thing you keep on yourself (KTTW card to plastic wrist band).
And as for not everyone being willing/able I highly suspect it's a willing issue. I have a hard time believing that there was only one CM at POFQ who has the ability to do this. If you come with 2 grand worth of $50 gift cards I would probably also tell you that it's not possible and to come back every night because adding those all to the reservation is a huge time suck during check in but that doesn't mean it's not possible. I'd rather push to get it done at check in and have a credit on my account than go down every night to pay off my balance.
Just saying that it's possible and extremely convenient and I am floored that people spend their evenings at the desk with a pile of gift cards every night rather than just load them all up front. It doesn't make any sense to me.