The 'big fella' No.9 is back in fashion, driven probably by Haaland. I think of it like an immune system. Current defences developed in an era where the big nine fell out of favour, and where most top teams used wide inside forwards as the main goal threat. Hell Liverpool with Firmino as a false nine almost did away with a central attacker entirely. So defences adapted, just like an immune system.
Into this mix, add an old fashioned physical centre forward, and defences aren't as adept at countering it, like an old virus that the body has forgotten how to combat.
Tactics are ever evolving and reverting to old ways to find an edge. Even 442 is coming back. It's just trying to present the opposition with something they are not equipped or aware enough to deal with.
Mitrovic, only ever a relatively limited and fairly average striker historically, is looking like a beast at the moment. I think this might explain it.
Rashford, Wilson et Al, all of a sudden look old hat. Although good players can adapt, and Rashford looks to be doing OK for himself. He'll never have the physicality of an old fashioned 9 though.