It's totally true, and more so true in a slaughterhouse. Blunt knifes cause strain injuries on joints, and make people use much more force than necessary, which comes at a loss of precision. And then it turns out, that with enough force, a semi-blunt knife will still cut through a kevlar anti-cut glove and hit fingers.

BUT!, once the knife is sharp enough for a job, and I mean for comfortable work, not just barely enough, then it's enough.

Giving somebody who never held a sharp knife in their life a knife that is so sharp it will cut their fingers without them feeling it (or even close to that sharp) is like telling somebody to run a coding agent on their system and not in a VM. Things can get bad really fast.

Most people (at least in central Poland where I come from) used semi blunt knives* for everything. Some would have a household knife sharpener or maybe even low quality sharpening steel like the ones you get in a knives set. Maybe they or their grandma had a butcher in the family. They will have nice sharp knives that can cut tomatoes without crushing them.

But with a knife that is sufficiently thin, a throwaway leather belt, a little skill and an hour or more of time, you can get a mirror-like polished blade that is so sharp you can amputate limbs in seconds. Just need to go through the joint at a correct angle.

That's how our grandfathers shaved.

* just realized I was typing plural for knives wrong - with an 'f'