Force = mass x acceleration
Power = force x velocity
If you have 20lbs of mass behind a 100 mph strike, you have less power than if you can recruit 34lbs of mass behind a 60 mph punch. (just throwing numbers out to point out that the raw speed of a strike is not the ultimate litmus for how much power (or potential power) there is there)
I was discussing this very point recently and did a strike on a student (who had a protective foam pad on his chest) from a half inch away. No way to get much speed but I was able to recruit a *lot* of my significant body in the punch. He had to bow off the mat and rest for a while after the strike. He later said it knocked a lot of the wind out of him and he felt it in his toes. And I've been hit by folk who do stuff like Systema and find that they can do a lot of damage with what appears to be a slower, relaxed strike. Same idea, you feel it throughout your body or in a penetrating fashion rather than as a "crush" on the surface. Heck, they even sound different when they land. A deep thud rather than a slap. FWIW.
Just a small tangent...