The issue is that there are real world limits on how warfare is conducted.
Even if Russia decided to whatever reason to do a genocide run on this bitch, going full on Dresden requires a large expenditure of munitions. Why expend those on turning cities into rubble, which makes them harder to capture, when they're better used on combat troops actually defending the cities? Fighting without restrictions is never possible because the real world imposes restrictions. The poor Ivan trying to deliver tank rounds and artillery shells to the front is probably driving a Z-marked civilian van that's going to have to be ditched and replaced by another civilian van in a week due to the stress of having to carry munitions in roads full of mortar holes. All because a truck got bogged down in the first week and a farmer took it home with his tractor.
What are "full war" levels? More people? That means more food that has to be trucked into Ukraine. More artillery? Someone has to haul the shells from the rail to the front. More helicopters flying close air support? They need jet fuel to run those turbines, and they can't fly comfortably into Ukrainian positions due to the proliferation of Stingers and now Starstreak missiles.
Right now Russia is playing their cards right by not overextending or blowing their load and depleting themselves of supplies.
Let me put it this way. If you're shooting, you're always running out of ammo.
Let's say you can get 600 rounds of artillery delivered to you every week. If you fire 100 rounds every day, you're going to run out within the week.
No matter how much ammo is stockpiled in Siberia, you don't have access to it. So you limit your fire rate to make sure that by the time you're almost out, you're getting new shipments in.
