I accidentally stumbled on the video of the most shocking injuries in hockey. In a couple of cases, the players were cut through the throat with a bowling blade. They are alive, but not the point.

If there is a possibility of such injury, why did nobody come up with any layer on the throat?

There is a throat protection, mandatory for players up to 18. The first thing a player at 18 does is throw away this saliva, the second thing is to change the grid that protects the face to a plastic visor that protects only the eyes at best.