Heavy use of cluster munitions (and land mines) was critical in allowing Ukraine to stop the second Russian invasion in 2022-2023 and stabilize the front lines. The notion that they kill civilians indiscriminately, or that it's unethical for defense contractors to build them for the US and allied militaries, is ludicrous and disconnected from objective reality.
Cluster munitions are highly effective at destroying massed formations of men and equipment. This forces the attacker to heavily armor up, which doesn’t work well against modern cluster munitions, and/or disperse forces across a very large area so that few targets will be within the kill zone of a cluster munition to limit their effectiveness.
They limit the ability of an attacker to mass vast forces in an area for a brute-force assault. Soviet doctrine was notorious for this kind of attack, so cluster munitions were developed as a solution. Russia still uses this kind of assault, so cluster munitions still work against their forces. Other militaries (e.g. the US) use doctrines that render cluster munitions ineffective.
Just about every weapon invented was developed to address a specific scenario where it is highly effective at shaping the battlefield. Some have become obsolete because those scenarios don’t occur in modern warfare, but there is still a lot of diversity in the practice of warfare.
Today 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:
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.
The following wiki article has a section on it. Cluster munitions allow you to saturate areas and prevent infantry from advancing. The issue is that some of the submunitions malfunction and sit around on the ground and injury civilians (particularly children since they look like toys at times) https://en.wikipedia.org/wiki/Dual-purpose_improved_conventi...
