I agree; they are also a companion. ;)
They say dog is a man's best friend; but horses are a woman's best friend! To me, anyway. LOL!! :P
They aren't a tool...or pet...they are more than that; most of us have such strong bonds with our horses; they are like a friend you can always count on. Working with our horses forms a great bond; & grooming is definitely a big part of it!!!
Just my take on it.