"Sharpening steel" is kind of a misnomer. They aren't designed to sharpen an edge by removing metal. They realign the edge after it's been bent and rolled over. The longitudinal grooves on the steel also catch and pull off burrs along the edge.

You don't use much pressure when you use a steel; one of the reasons it's held in the hand. You use it regularly, a few quick swipes, while cutting and carving. Kitchen knives will last longer when the sharpening steel is used regularly. You go longer between actual sharpenings where more metal is removed from the edge. If you've ever seen the stubs of knives left over after butchers and processing plants use them up, you know what I mean.

Most importantly, sharpening steels work best with the relatively soft steel used in kitchen knives. The softer steel edge will roll over and bend while cutting. It's that edge that gets realigned. Better knife steels with a harder heat treat will microchip instead of roll. When they're dull, it takes a stone of some type to remove metal and sharpen it.