Not to turn this into a military strategy thread but....
There is something to be said for highly mobile anti-armor weapons in possession of the defending force, but there is ample evidence that Russia simply does not have enough manpower to use its tanks properly.
* There are many cases in which a three-crew tank is manned by two people (there is no commander).
* They don't seem to have enough cannon fodder to act as a filtering force - the perimeter around armor to make sure they are not targeted with standoff weapons.
The reports of the tank's death are greatly exaggerated.