I disagree with this. Bruno played in a 3 man midfield at Sporting. Pogba played in a 3 at Juve & plays in a 3 for France. There's absolutely no issue with them playing in a 433, the reason they can't do it for United is the coaching is piss poor.
The keyword was and. Bruno and Pogba. In both their cases they were the most free, unshackled from positional responsibility CMs in their previous teams. Having one of those works, but having two of those in your starting XI, surprisingly doesn't seem to work that well.
The coaching also sucks, agreed.