I dont understand treats?

Why do people use sugar cubes, hay cubes, and peppermints..... I know their possible stats based on the catalog list but wondering if they give multiple stat boosts across all disciplines. For instance if i feed a horse one of these treats, is it possible to get a speed stat increase plus an endurance stat increase or does it only give you one type of stat increase? Any and all information on these treats would be very helpful! Thank you Everyone!!!

Multi-stat treats will give a random boost across all of the stats. For instance, if you use hay cubes on a horse, that horse will get a random point increase ranging from 0 to 2 for every one of their stats. Multi-stat treats like this do not target stats and will not give discipline-specific stat boosts, which is one of the reasons players will choose not to use them. If you want to increase only your horse's discipline stats, you will have to rely on using single-stat treats like green/yellow/red apples instead.  

Ok that makes sense. Thank you very much :)