The impression I, and I think most people, had was that newer stuff was radically better than older stuff, but it turns out it's not really significantly better. Mobile artillery is mobile artillery, no matter how old it is. Aircraft is in a similar situation. Modern fighters are stealthy and can engage well past visual range, so "dogfighting" is dead. Old aircraft that are not like this are obsolete and are dangerous to fly.

The example is the first Iraq war. Sadam had one of the largest armies in history, and was ready for the "mother of all battles". Instead a smaller but highly sophisticated invading army picked it off with minor casualties. The lesson supposedly was that smaller but more advanced units were better than lots of units.

But when you think about it, none of this makes sense. How is a tank from 1970 worse than a tank from today? It has more armor, a larger gun, is better at deflecting rounds, maybe the turret spins faster, or it's able to track targets better. But at the end of the day, none of this matters if the training isn't where it needs to be. And it really does not matter if someone lobs a piece of metal so dense that it will go through your tank like butter regardless of the armor.

Also, there's the cost factor. The bigger your tank, the more expensive it is, and the harder it is to repair or replace. When you can't have a lot of them, then what? Smaller tanks to support them? Then we're back to 1970's tech. The same story with airplanes. At a certain point, if you are afraid to use your super advanced air superiority jets because they're too expensive to risk losing in an accident or a statistical situation where someone inevitably gets lucky, then it's almost like you don't even have them.