Well do you think navy seals shout to each other: ‘FOLLOW ME!’
or ‘I NEED AMMO’.
Unless they want to trick the enemy into believe they are out.
They don’t do that in real life because that gives away their position.
Sure… in this game your enemies can’t here your shouting ?! Which is unrealistic isn’t it. But it’s a game it doesn’t have to be realistic, it has to be fun !
And I think having a hand gesture… like waving… like get over it…
could be really funny… if not just to play around with
Like I wave to you: ‘get over here’. And then I shoot you
We used to play around in rtcw with all kinds of stuff. 
But it could have some serious game play addition as well. People who like to be sneaky and quiet with stens and silencers can use those gestures to move in a more assault-squad team like movement.
Like a fist meaning hold position don’t move.
And other signs… I am not an expert at navy seals and squad like hand signs… but I leave that to the game designer to figure out and inform the player about it 
Now most people just run like dogs after each other without real communication… Expect maybe follow me.
But that’s it.
With gesture you might be able to point… and wave… like you go over there… and you go ever there
or come closer… or stay there.
That’s like non-verbal communication 
I am 100% sure it will add to gameplay 
Addition:
Or maybe a combination 
MUST HAVE 
This voice message should be added:
‘STAY THERE !’ 
or
‘HOLD POSITION’ 
But Stay there is more dramatic
like during an airstrike, thinking blood.