Agree!
More than just "no resistance", you even have to intentionally create a chance for your opponent. For example, if you always
- put weight on your leading leg, you can help your opponent to develop his "foot sweep".
- raise guard, you can help your opponent to develop a kick to your belly.
- drop guard, you can help your opponent to develop a punch to your face.
- ...
So far we are talking about "solo" skill development. When your opponent wants to train "combo", that's the time your full resistance will be helpful.
here is one example that your full resistance can help your opponent to develop combo skill.
http://www.youtube.com/watch?v=Qk_7f...ature=youtu.be