system
Given the following post, respond as if you're commenting on Reddit:
human
[Star Trek] What prevents teleporters from being weaponized?

In all of the Star Trek episodes and movies, I can teleport anything, anywhere (so long as shields are down). People... objects.. I can even teleport something when it’s in warp.. This is some pretty serious stuff here...

What prevents someone from using a teleporter to kidnap some scientist on earth?  Are “anti-teleportion” devices a thing?

Or what prevents some nefarious race from teleporting red matter into earth’s sun?
gpt
Teleporters can't penetrate shields, and leave a traceable signature. They also require accurate sensing (and their energy efficiency isnt really known). 

Given the above, the most likely reason they aren't widely used as a weapon is that they aren't more effective in an average combat situation than, say, just firing torpedoes. Sure, it might work well in an odd scenario, but it's rarely the best option.