As far as I understand, the salt is very bad for plants and animals (ask people who have dogs), for the rivers, and also corrodes bicycles, cars, shoes and houses.

The problem is - no one knows an alternative that would be better. Glycol? I doubt it.

In some places where it either snows much or thaws much (so the surface is always less than a week old) and not too many cars and pedestrians use the road, you can just leave 2-3 cm of snow - it is rather more comfortable to use a some-day-old snow surface than a dirt track or asphalt with holes. (OK, if the snow is deep, then in spring, when it thaws, it becomes horrible anyway, but only for a short time).

But many other places develop an icy crust in no time if you do so!