Yeah that's true but personally i don't need it. You should always be aware of the map for possible ganks and shouldn't rely too much on your team for calling misses, as sometimes they dont. So if you die its simply cuz you've failed. At 6 you should be fine to get away from ganks with your turrets + uti to slow people down and a clever use of flash to get out of it so yeah grenade's till later :)

No grenade at all until end game? fail..
you should get at least 1 rank early on in case of gank