Smilie, I have trained, shown and generally been around horses for over 50 years, what it all comes down to? Enjoy your horse, meaning if you want to give the animal a treat because it makes you feel good & the horse feel good, then do it! If the horse is a brat, and start grabbing for treats, then don't, simple as that. We spend lots of dollars to keep these animals, might as enjoy them. Sometimes I don't have any treats, so the horses get none and don't miss it, no big deal, sometimes I do, and they enjoy it. If I can get the horse to come to me 5 minutes sooner if I have special treats, fine, if not, let him run around for 5 minutes, he always comes around to me when the silliness stops. Life too short to sweat the small stuff, enjoy your horse.
Sure, everyone can handle their own horses however they wish, but forums are meant for horse a handling advise that fits all situations and level of experience. We all make exceptions that work for us, gained , through working with many horses, but that we don't actively promote .
I also raised horses for many years, that were sold, thus not handled by just me all their life. It just made more sense not to have those horses associate humans with treats. Whatever new owners did afterwards, never influenced the way that horse was when sold
A child, or in experienced person would not notice when that horse, used to being fed treats, stepped over the line, and also why professional trainers don't make feeding hand treats, part of their training program
If you are the only one handling your horse, go for it, if feeding treats makes you feel good!
Those accidents, in the link I posted, were not all due to a horse being aggressive, fed hand treats, as in the woman that lost part of her breast