When someone has not learned something, it does not mean that no one tried to teach. We do not know what the staff did or did not try to do about FTs. There are many possibilities.
One is that the staff never noticed what our resident experts have, and that only in the Oklahoma game did someone say, "Hey! Doke can't shoot free throws! His form sucks. Anyone notice that flying elbow before?" "Huh? No, not me." "Me neither. Doesn't matter, though, cuz he will get better. What the hell."
I think it is more likely that they noticed the problem, but it was a lower priority than a few other things. Like getting Doke to set picks and defend the rim without fouling out (a work in progress), learn up-and-under footwork (coming along nicely), and teaching him a hook shot so his range can go all the way to 5 feet or so. A few minutes of trying to improve FTs enough to get by was likely the only time available. 43% probably seemed adequate so they could get his action lessons to take, and until the OU game, may have seemed worth the risk. Agreeing with @JayHawkFanToo does not happen all that often, but I think his discussion of resource allocation and priorities is right on.
For everyone who thinks that if they tried to teach him he would have shown improvement, I would just point out that it took several technicals before Doke stopped hanging on the rim (including Italy), and he is still getting T'ed up for taunting (Doka Dunk Face). Maybe he is just not a fast learner, or, more likely, in stress he resorts to old habits like all of us do.
One thing I have wondered about is whether his teammates, with whom he shares a dorm with a practice court available 24/7, have been tasked with helping him, or whether they give him in-game advice on the bench.
Why did Shaq and Wilt not make quick turnarounds in FT success? A question for those who thinks that Doke's poor form is the result of staff not trying to teach him. I think at least one of Shaq's teams even hired a dedicated FT coach, to no avail. Gross negigence by all the coaches he had? Or poor learning on his part?
Self's comments have given everyone a feeding frenzy for how stupid he has been. A good coach--takes the blame by making it look like it the problem is just his obtuseness rather than a player who won't listen or who at least forgets what he has been taught.
Gross negligence. "We all know that is the only answer." Blah, blah, blah.