And frankly, swords cut pretty easily.
Yup. And I can't count the number of times I've had someone show me something to "improve" a sword cut's power (huh?) that really only showed they'd never really cut anything of substance with a real sword. Like everything else there are a lot of details...
I agree with the whole context issue. I use my suburito for tanren. Which I would hazard to guess is the most common reason for it across many styles. Not all, of course, but quite a few emphasize the same things. Early on I was told that doing a lot of cuts in a row tires out the beginners arms and shoulders. As you improve over the years the fatigue works its way down your back and front until it becomes a sort of ab/back workout. A suburito will certainly give you a lot of feedback as to where the power is initiating. Most would say this means you've learned to do it right. Maybe it's more accurate to say you've developed the longer, connected structures better and are better able to control where it is coming from.
But again, gain of salt... Just random observations. I like my suburito. White oak. Bugei Trading had a bunch of them a while back and I couldn't resist taking one home. They haven't been able to get them since. I wanted to buy a couple for friends. Great tool for training. Do it every morning.