Yes 4 second timer and an entire squad closing to literally hand-shaking distance is totally comparable to 1 dude crouching and shooting a detonate on impact grenade with bugged sound files from almost maximum small arms range.
I made a thread about this issue pretty recently too. Bonus points if the model firing the nade has a G43 and he doesn't even crouch and just shoulder fires the nade with no warning lol.
Gren rifle nade got nerfed so many times already to a point where it is almost impossible to oneshot wipe a squad.
Many times there actually is a sound queue.. and the rifle makes a unique sound upon launching the nade.. + it takes around 3 seconds for the nade to land. So yes, I think there is also the player to blame if he loses a squad to it because he didnt pay attention at all on the few occasions without a sound notification.
Or do you also complain that there is no audio warning queue before a tank oneshots your squad with a lucky shot?