>>508397510Because in order to gain ground quickly they would need to use armor columns or large groups of people, which would get destroyed by artillery. Fast progress means many losses, they learned this early in the war.
Now they are slowly inching forward while minimizing losses and relying on artillery and glide bombs to do most of the dirty work.
Every single day they are capturing small towns here and there, and Ukraine has no counter strategy against this so far, other than wasting their drones on single soldiers or groups of 3-4 at max.