Adding “loving” to “limits” does not make the limits non-coercive, it just adds confusing mixed messages to the coercion. The parents are coercing the child while acting as though that is not what they are doing. They are pretending that they are not responsible for the distress they are in fact causing.
Ultimately, we all (including our children!) have to do what we ourselves think best, what feels right to us ourselves, not what someone else says is right. We are all moral agents in our own right. When we self-coercively override our own wisdom and do what someone else thinks we should be doing, we are acting wrongly by our own lights. No good can come of that. Treat this site as a source of speculative guesses and interesting arguments, not as an authority you should obey.
In this heyday of scientism, all sorts of experiments are performed to back up every conceivable view of education, and people simply cite the ones that confirm their prior beliefs and ignore the rest. Hence they are asking other people to abandon their opinions in deference to a type of ‘evidence’ which they themselves would (quite rightly) not pay a moment’s attention to if it had gone the other way.