I disagree with this. I think De Ligt is a natural leader, which means he can replace Otamendi or Kompany in the way that Stones, Laporte can't.
You watch the way he's carried that Ajax side and he's their talismanic leader, the Puyol/Kompany/Terry/Ramos figure. He organises and controls his teammates, he scores big goals (Spurs, Juventus, Feyenoord in the cup semi), he's calm when everyone else is panicking, he takes on responsibility to stop the oppositions big players - in the Juve game he was virtually tackling through his own players to stop Ronaldo at times.
I don't think he'll sign for us, but I think the difference between him and all the other big, young CB signings recently - Pavard, Kehrer, Stones, Laporte, Hernandez - none of them have been leaders like De Ligt is.