Where things go wrong is when uke is told to follow, no matter what. Even if nage tenses up and yanks his hand away, even if nage turns his back, even if nage tries to simply shove uke off balance, uke must "follow." No matter how badly nage does the technique, it is uke's responsibility to "follow."
For that reason, I prefer phrases like "take nage's center" or "continue to attack" over "follow." At higher levels, it must be possible for uke to "win" if nage commits a sufficiently large error. Otherwise, nage will never learn where his errors are.
I think there is a third way. I won't say it is preferable to what you are referring to but it IS another option - and where I train, where the norm does not permit uke/nage to switch roles, it is the one I use.
If nage tenses up, turns his back, etc I continue to follow (yes, continuing the attack and as if I am trying for nage's center) - but rather than actually trying to get nage's center, I follow the lead and as long as we can maintain connection, go where rightly or wrongly I'm actually being directed. If nage is contracting and spiraling me in, rather than extending and spiraling me out, this might lead me to a place where my free hand naturally gives a little atemi. If nage wanted my imbalancing to be forward with a fall over here, I won't make the course correction to match her expectation, but will imbalance where it actually is and fall where I'm actually being put - sometimes to nage's consternation.
So I try to be as accurate a mirror as possible of what nage is actually doing.