It wouldn't be as easy as it sounds.
A properly tied full Windsor is awfully tight and takes a little wiggling to tighten up into the collar. Considering that the tail is generally put into the loop in the back of the tie, it would be hard to get to. Even if you did grab it, it's not likely going to cinch tighter by just dragging on it.
Now that's not to say you couldn't still just grab the tie in the front, pull it around to the back, and choke the absolute shit out of someone! Using that logic though we also have to do away with scarves, purse straps, and necklaces below a certain "gage".