Anonymous“What damage do you think such explanations of the past tense have done to ESL students learning?”
Negligible damage, I think. That statement alone is not sufficient to influence learners in general, taken out of context. To have an effect, learners would have had to take that short sentence literally, understand its meaning exactly, generalize it to every context, remember it, and then not let anything or anyone else affect their cognition with respect to that "rule".
Not likely, so negligible damage. If you think otherwise, prove it.