Rashford is the latest in the "wasted on the wing" nonsense that is prevalent in British football. It was the same with Rooney or any other promising forward who is shunned to the wasteland that is the flank of the pitch.
The number 9 role is too pivotal in modern football to play such an inexperienced and inconsistent player in that position. I also disagree that playing Rashford right up against the defence is his best position. He thrives in space with his speed and will get more of that by starting in a wide position.
The insinuation that his finishing suffers by playing wide is nonsense. Ronaldo, Messi, Mbappe, Salah, Mane, Hazard all manage(d) to score plenty from a wide position. In modern football, wide players in a front 3 are forwards and often can have more goal scoring responsibility than the number 9. If they can't get into goal scoring positions when playing wide in a front 3 it shows poor positional play.
The biggest obstacle to English players being prolific from wide areas is the stigma that playing wide seems to have in England and the fact the players would rather listen to the media drone on about how the coach is ruining them by playing out of position rather than learning and improving in the role.