Not everyone does. I use a BodyShop synthetic as a travel brush. It doesn't hold water as well as a properly broken-in boar brush, but it does ok, and dries almost completely with a flick of the wrist. I could get by with it if I had to.

If you're looking for a good quality brush with some real spine to it, take a look at Omega's selection of boar's bristle brushes. They mostly ring in around $20 and really get the job done, especially the biggest of them known as the "Professional"

Best Regards

goshawk