Not always to the same extent, though.
In warmer weather, my horse always gets hosed down to remove any saddle/sweat marks and to get the mud off his belly and legs. Not usually a bubble-bath, just a plain water rinse. Then all the excess water is scraped off, and I walk him over to a grassy area to let him graze while he dries. He gets a final rub-down or brushing, then goes back to his stall.
In cooler weather, if I DO hose him off at all, I only do his legs and belly just to get the mud off. If he is hot and sweaty or if it's really cold, I put a wool or fleece cooler on him so he won't get too chilled while he cools off. Sometimes, if the weather is really really cold, I won't hose him and will let the mud dry, then brush it off with a stiff-bristle brush or the cactus cloth.
Most of the other people at my barn used to tease me about the amount of time I spend caring for my horse after a ride. Many of them just throw the horse back in its stall when they are done riding, saddle-shaped sweat marks and all. I prefer not to put my horse back in his stall until he is clean and comfortable.