Could be useful and useless at the same time. As mentioned above players may rebind f1 key to another button and also if a player gets knocked down he will turn on f1 and he knows the timing when player wakes up and will turn it off. And I am sure there are many other ways to still use f1. Anyways implementing this will prevent many of newbies from using it, who have no idea how to use f1 in other ways.