If we're being charitable, Dorgu is adept at creating width. He's neither a superb crosser, nor very good at effectively driving buildup play, nor at defending. That's not a dig at him; just an observation that he's a young player who is still developing and definitely isn't yet for a consistent starting XI spot.
The only reason he is a United player is because Shaw was injured and Amorim found himself underwater after a terrible holiday run during which he was having to rotate Mazraoui, Dalot, and Malacia at LWB.
Under any normal conditions, a player like Dorgu would be an understudy to an experienced starter so he could develop slowly - not as an immediate starter at Man United.