[vkazanov]

I don't know much about Mongols in Central Europe, so probably true: they were far away from the steppes, probably lacked siege machines, etc.

Also, in the lands of Rus' stone fortifications were a very rare thing - there's almost no suitable stone for contstruction, so most castles and fortresses were wooden, so they did burn.

None of the stone fortresses in the north, where there are suitable materials, were plundered, AFAIK, so you must be right.