alt Hacker NewsToday that role (strongly discouraging grouped formations) has been occupied by drones.
The current UA/RU front is a 30km deep kill zone crossed by FPV craft (and discarded optic fibre cables) in which the largest effective group size might be four or so soldiers. Tanks are all but useless as sitting ducks.
Reuters made a surprisingly good infographic / interactive feature on this this past July:
<https://www.reuters.com/graphics/UKRAINE-CRISIS/KILL-ZONE/zn...>
Some aspects of modern warfare seem to be taking the classic idea of light infantry and dialing it up to 11. They have little armor or heavy weaponry but are such a fluid sparse target and have such a small logistical footprint that they are expensive and difficult to root out.
The modern version of this allows the same soldiers to command heavier, better weaponry via remote control that is asymmetric to their logistical footprint, enabling them to shape a battle space that would not have been possible historically.
Of course these things ebb and flow. I imagine the solution to this problem is something like autonomous drone swarms with advanced sensors that can systematically sterilize an area of any hidden soft targets. Sparsity would not be much of a defense in this case.