There are router router bits with skew angles. I'm not sure which one started that. It may not have been possible until CNC manufacturing took over the process.
The principle is fairly simple. Instead of having the cutting edge attack the wood all at one time, as in when standard planer or jointer blades make contact, the cutter only makes contact with a small portion of the wood at any moment. This both requires less force on the part of the cutter and leaves wood next to the cut intact which reduces the risk of having a large chunk break away due to a weakness in the grain. There may also be some gain by coming at the grain from a slight angle, just as hand planing is easier going cross ways than longitudinally.
I see guys occasionally trying to sell router bit sharpeners that just grind the edges as the bit spins in the router. This leaves you with no relief angle. No relief angle means you are scraping wood off instead of cutting it off. The relief angle is fairly important and it's around 25 to 30 degrees as a rule.
Someone I consider a master woodworker once told me that a master woodworker is not someone who never makes mistakes. He is someone who is able to cover them up so that no one can tell.