Re. Liverpool, and this is a really important point, worth noting that the Dortmund teams Klopp built his reputation managing always had a world class centre forward (Lewandowski then Aubameyang after the former left to Bayern).
So it's not like Klopp chose this formation without a traditional centre forward on purpose, the reality is in his first few seasons at Liverpool his squad contained at least 2 or 3 traditional centre forwards.
I'm not going to say he stumbled upon it by chance but the reality is, like all good managers, he tinkered with his system to accommodate / get the best out of the players he had at his disposal but crucially identified where the weaknesses in the squad were then went out and spent big and his signings have delivered.
Man U need to play to the strengths of the Rashfords & Martials of the squad by playing them in their strongest position and going out and buying proven quality for the other positions they lack. Unfortunately for Man U, both Rashford & Martial's best position is inside forward on the left hand side, cutting in onto their right foot.
For me, Rashford has big potential, Martial will never be more than a squad player at the top level.
The big positive for Man U is Solskjaers signings all look like great acquisitions
McGuire - easily your best DC
Wan-Bissaka - your best DR and massive potential
James - bargain, bags of work rate, great pace and potential
Fernandes - creativity you've been sorely lacking