Just remember that, unless your goal is just to kill everyone and scorch the earth, the aim of warfare is to occupy and control territory, which at some point necessitates humans to do the occupation. Nobody is yet trying to create permanent wastelands inhabited only by robots. It may become increasingly dangerous, but whether it's helicopters or some other means of transportation, you have to get humans into the land you're trying to take.

There are limits to autonomy as well. Presumably they mean these things can find targets and maneuver in real time without continual human intervention, but they still have human operators and someone has to give them a target. My brother-in-law works for Anduril, as a forward-deployed trainer of the drone operators. There are very much plenty of humans involved here. They can't just ship you a pallet of machines that you turn on and then they go fight a war for you.

Also remember that exactly what you're describing (all the grunts are pinned down by artillery and can't move) is exactly what happened in WWI. That didn't mean it was the future of war. Offensive forces adapted. Heavy armor, airborne troop insertion, long-range counter-battery. Having the upper hand in an arms race is never enduring. The other side always adapts.