Nope. I don't agree with that statement, at all. I don't think there's much benefit to fiddling with grappling via unpartnered activity, except as a filler where a partner isn't possible. And it's a poor substitute, because so much of the mechanics is different.Have to disagree with you on this.
You use solo drill to "polish" your technique so you won't build bad habit. "Polish" means to remove all sharp edges.
You polish grappling by grappling. Stylized (what in NGA is called "classical") versions can be used to reduce the variables for this purpose, but without a partner, correct balance becomes incorrect and good body position becomes awkward.