Yep, that's the thing about the defenders in this game:
They have stuff that CAN kill/hurt you,but mostly they are supposed to do three things:
1) block of easy access to the objective and guiding the attackers down the path the defenders want them to go
2) slow down the attackers as much as possible to make the 5 minute timer go down
3) have the attackers make as much noise as early and as often as possible to know where they are
ubisoft, as you correctly say, basicaly balanced the game not around defender abilities necessarily killing attackers, but about giving the defenders the tools to properly setup to defend. they are still supposed to use their guns and not rely entirely on gadgets.
This is true for the defenders too btw, with only small exceptions like Fuze