“the prevailing wisdom being that as long as our children never hear the words “no I won’t allow that” we can eradicate OTD.”
I dont think that is the prevailing wisdom.
The issue here is it is important that we teach halacha and then strive towards chumra growing beyond the minimum. When the halacha keeps changing it makes the whole thing sound fake. Rabbi Resiman said this in a during hsi motzoei Shabbos shiur towards the beginning of last year. First the halacha was skirts have to cover the knee then the halcha became past the knee now it is taught 4 inches past the knee (unless it has gone further by now). This leads to confusion and certainly has potential to lead to rejection. Look at the OP who readily admits regarding the very issue she is commenting on “Hello? I’m confused.” Thats isnt to say all people with confusion go OTD, but it is troubling that a graduate of our school system is “confused” about such a basic issue. Is it any wonder if someone weaker, who is similarly confused decides the reverse that if this has no source, then probably covering hair after marriage has no source and who knows what else.
I dont think anyone says saying ““no I won’t allow that” causes kids to go OTD. The concern is arbitrarily saying ““no I won’t allow that” and when standards seem to shift arbitrarily is (part of) what causes (some) kids to go OTD.