So can mages also repair smashed gates? They should if they can repair bridges.
Just because its a "special ability" doesn't mean it can't be utterly stupid. And this is.
Any army just need a few soldiers to level up enough to smash a gate, and sieges will take minutes. They can just let that soldier kill 50 other soldiers to gain the XP. The loss would be lower than gong through the actual siege, anyway. Whoever came up with this ability should do Tom and Jerry episodes instead.
Kind of how the Warden in DA:O kills over a thousand people, potentially single-handedly?
Or how any Bioware protagonist can kill fire breathing artillery without a problem?
Seriously, you're acting like an RPG protagonist doesn't already render the very concept of military tactics and militaries irrelevant by doing things at level 3 no real world soldier could ever, ever do.
Realism complaints in an RPG are absurd, because the very existence of the plot of the game is a middle finger to reality.