Murray - let me take a crack at this:
You can certainly win with an "old-school" offense.  But, in order for that to work, all of the other pieces need to be in place.  You need a solid defense, good special-teams play, and a QB who can at least make some throws when you need a big play.  
And - to make that happen, the salary cap has to fit. 
That is the biggest problem with the Vikes - the pieces don't fit.  An expensive QB playing behind a below-average O Line, and a defense that falls apart at the worst possible times.  
this is a poorly-constructed team.   I don't care how good Dalvin Cook is.  He can't make up for all of the other deficiencies. 
in the end, the goal is to outscore the other team.  if you have a good defense, you can win with an old-school offense.  If you don't have a good defense, the only way to win is to put up as many points as possible as fast as possible, and it's hard to do that by running the ball.