Contact time changes with force, tip offset and even tip hardness, in a normal range of 1-2 ms. That's all been demonstrated in clear and convincing ways. The theory of controlling contact time some other way, and why it would be beneficial, hasn't really even been clearly proposed.
But as was said above, if that visualization improves the effectiveness of somebody's stroke then it's a good tool, damn the reason.
pj
chgo
Ahh yes, the old swoop stroke. I tend to agree with you, but to be fair, all that has been established is that a handful of amateur players cannot make it work. If Mike Massey can't do it then I'd say it is probably impossible.