Yeah, this one activated all of my latent "rules should model reality" urges, and I had to smack them down and tell them to shut up, that was important was their use in the story and so forth. As an MC, I'm not gonna stop a character from throwing a grenade because of the tag in the line (breaking the rules! oh noes!) but I won't complain if an MC is like "you have to get closer in, where he can attack you too, if you want to use that".
Two quick asides: 1) grenades (the typical fragmentation kind, anyway) are way heavier than you think they are, and a 100 yard throw would be pretty freaking amazing, good on you if you can do that, I throw like a girl that can't throw well, 2) their effective range/deadliness is also more than the most movies would have you believe. If you tossed one casually into the other room and hid behind an interior wall, you're probably in a bad way.
But again, that stuff is not important unless you think it's cool