yeah but the only problem is that the moment your opponent (or partner) feels your strength he/she will resist. If you are relaxed and utilise Ki it will be harder for them to stop you. This can be evidenced through static gripping such as katatetori where the moment you use strength anyone strong enough can stop you by resisting.This tends to happen when you mind and body are together, which is not how me and the other students are trained
There is something to be said for not just grabbing someone and trying to man-handle them around. And in not tensing up everything at once and making yourself unable to move. However, people don't feel strength, they feel force. It doesn't matter how that force gets there - whether it's ki or body mechanics or what have you. If you're applying the same magnitude of force at the same angle, they're going to feel it the same.
It's like if someone grabs your wrist to stop you moving it forwards - if you hold your wrist straight and just try and push into them it's very hard - if you rotate your wrist it's fairly easy. If they rotate their wrist the other way it's hard again. Nothing to do with ki, just different muscle groups with different degrees of tension being put through them.
I suspect a lot of the problem people have with the idea of strength is that they think it should feel like they're putting a lot of effort in. And of course to feel like you're putting a lot of effort in, frequently, you have to tension opposing muscle groups to get enough resistance to push against - which results in less overall force being generated in the desired direction.