A lot of high drafted players turn out to be busts or at least disappointing.

If you go through the starting tackles in the league, the vast majority of them are R1 picks. That's not a coincidence. Nor is it a coincidence that next to QB, a good LT is considered one of your most valuble players on offense. The contracts they get even reflect that.
Go back and look at who made All-Pro. All-Pro is determined by people who know, not fans, so it's the real deal.

There are a few outliers (Terron Armstead, Mitchell Schwartz, and.... David Bakhtiari) but the vast majority of the All-Pro OT's are not just R1 picks, but top 10 R1 picks.

In other words, you are incorrect in saying drafting OL early is never good. There is plenty of proof to back that up.