England massively missed Rashford all tournament. There was no pace outlet, and the left-hand side was non-existent in most games.
Rashford would have also brought the best out of Harry Kane, and when Southgate is playing more counter-attacking style football, he is your best pick.
He got 3 goals in 144 minutes last World Cup. In terms of balance and who suits how Southgate wants to play he should have taken Rashford.
He may have had a much worse season than the likes of Bowen, Foden, etc., but for England, you know he can deliver, unlike the other two.
Southgate should have focused on balance rather than trying to accommodate all his best players in same team.
Rashford, Kane, Saka have always been Englands best/ most balanced front line.