In Mythruna, the players are the only ones with the power to assemble and disassemble structures so easily. An NPC is unlikely to sit there with a pick-axe chipping away at some block until finally it comes free and then he has to haul a two-ton piece of rock somewhere. Not the easiest thing to steal.
NPCs will actually have to build their stuff, too... not just plop blocks down. This would be one easy way for a player to ingratiate themselves to an NPC, by helping them build their structure (how exactly that works still TBD) since a player can do in minutes what it would take an NPC several days to do.
