As Phaedrus indicated, it's all about the operator. Light, quick passes are fine so long as the blade never gets uncomfortably warm to the touch. A nearly worn out belt can get you in trouble in that regard. I practiced a lot on beater blades before I was comfortable working on good ones.

A belt sander is not necessary for domestic kitchens. Nor are spendy knives, for that matter. Generally, the best blade for the job is a well-maintained blade. I've been on a quest for years to teach people how to do basic hand grinding and steeling (realignment) so they can get decent performance from the knives they already have.

Since I repair and recondition hundreds of knives a year, a belt sander is just about mandatory. Some of those are literally rounded off, and it takes forever by hand. I still hand-finish good quality blades, though; I haven't got around to buying a buffing wheel.