It's the players that need to make the play when the DC puts them in the right spot to make the play. I disagree with all of it. The DC puts the entire product on the field (scheme, play calls, tackling, personnel, etc )

I don't think I've heard someone say they shouldn't practice tackling. That would be wrong too. So much technique is involved in tackling and players come from different HS programs and come to college at different levels. It needs to be worked on.

You don't have to do the Oklahoma drill 2 hours a day but players do tackling circuits, tackle wheels, wrap exercise balls, etc all the time in camp.