Why can't it not be about both? Capturing land when available and feasible and inflicting damage to the Ukrainian military? At this point, both are being done. When the war front is so big, the rate of advancement is slow and the Russians don't want to lose too many men so they are cautious. This not the Soviets rolling through Eastern Europe trying to chase the Germans.
And also, Marinka is being attacked by Russia now so only a matter of time before it falls too.
Fierce fighting:
The Russians have attempted to break through the Ukrainian defence on the Marinka front over 30 times from the beginning of 22 February until 18:00.
www.pravda.com.ua
Just like Avdiivka, very hard fighting. (I am using a Ukrainian source here to be fair to all sides)