Can you name fearsome punchers who weren't automatically great finishers and guys whose punch wasn't necessarily dynamite but they knew how to finish?
An example of a very powerful puncher, who was not a great finisher, would be Cleveland Williams. Everybody who shared a ring with him, named him as being among the hardest punchers that they faced, but his KO% fell off dramatically when he fought ranked opponents. An example of a very powerful puncher, who was a great finisher, would be Muhammed Ali. Nobody named him as being among the hardest punchers they faced, but he had a high KO%, and it held up when he fought elite opposition.
Both are excellent examples. I would also say that Sugar Ray Leonard was an excellent finisher that relied more on relentlessness and skill than just straight power to get guys out of there.
It must be said that power alone, even the most incredible power, will not make you a finisher at world level.