[member="Silara"]
This was not an expression of physical capability, but with the organization of his headspace. Only a person who believes in God can pick up quarters left by God. An Atheist just finds money people dropped. Darth Bane just wasn't good at it because he was more into elementary models of power.
EDIT: Additionally, as hip as Sith Alchemy is, it's also inferior to, y'know, a basic Lightsaber. It was, once again, trying to manipulate unknown forces through elaborate means to yield results. Eventually, people didn't need it anymore. That's why Sith Alchemy also went the way of the dinosaur. Both Sith Magic and Sith Alchemy are ANCIENT arts of a dead species. They went away because they were inferior in comparison to the way they're practiced now.