it is nothing compared to the actual war.
Only an idiot would think any army tries to kill you in training, so of course 'it's nothing compared to actual war'. They spend virtually no time in engaged in combat, which is extremely anticlimatic. The majority of the casualties come from two girls, and a booby trap IIRC. The film seems to spend more time with the prostitute than the ultimate sniper.
The danger seems sporadic, and random, when it's there at all. None of the dumb young soldiers seem mature enough to realize it, let alone be systematically traumatized. This seems a very commonly offered but weak argument in defense of the film. More than half the movie seems to be about boot camp, so that seems to point that the major themes of the film aren't really related to combat per se.
It seems more of a commentary on how you change normal young teenagers, into semi-deranged, thoughtless, robotic, automatic instruments of killing. Starting with the uniform haircut, to marching in lock step singing a jaunty war song.
The irony is that it worked so well on Gomer Pyle, he who went completely psychotic prematurely. Ideally isn't that supposed to happen on the battlefield? Compare him to the gunner in the helicopter, murdering random Vietnamese civilians indiscriminately, and jokers twang of conscience, but ultimate indifference. Recall how the recruit who thinks it might be worthwhile learning a little of the language (and maybe history?) of the country they're being sent to, is almost brushed off as eccentric. The reasons for the war seem mostly incidental and the objectives arbitrary to their experience, except for each soldiers personal desire to survive. It seems incompetently led considering the chaos and confusion in the street fighting against the lone sniper, and blowing up huge stretches of jungle without so much as sighting the enemy. One empathizes more with a lone girl who puts a grenade in a helicopters after seeing her entire village destroyed. Maybe she wasn't even a VC before that morning, but knew where one of their stashes was and improvised. Who would ever find out?
The collective punishment of the recruits is matched by the collective punishment of vietnamese.
Look at the arc of the Joker, starting as a pacifist (was it religious?), and ending with him killing a dying girl. It's not so much anti-war as it ignores it almost completely, while being rather anti-soldier.