They are still dangerous in the hands of a sensible person.
Hypothetical Scenario:
Im creeping up behind a bush, look out, no one is there. I sprint for cover, and someone else sprints around the corner and we meet. Even the most sensible person will panick and spray the opposing player. Rarely will someone stop and thinking calmly 'wait, this is too close'.
Without a full face mask, you are at risk. It's entirely up to you if you want to take that risk.
With a full face mask on, there isnt much that go wrong short of being struck by a lightning bolt.