That it true.
But to be fair, the soviets are lacking an units between. Only some modders could make something to fix, e.g. PTRS versus plains (as ability etc.) or a special AA structure.
edit: but its no reason to simply counter everything with one vehilce. 2 are enouth to kill everything in air.
meh, it was an issue before when tech was split (and back then the quad couldnt shoot down anything anyways) but now the quad is accessible and will still eat up cap (and those munitions to unlock) so it has a heavy impact with little else by means to reap rewards while ALSO being squishy. its a glass cannon of AA.
meanwhile the only ost armour that doesnt help shoot down planes iirc is the werfer, so the ostwind doesn't NEED to be a god at AA because volume of fire does the trick.
if anything the quad, while defintly disrupting air power helps you as a player take the ground as there will be less mines, strikes, snares and abilities. manage to take it out and you strike a hard blow to the enemy as well.
like i said, it could be toned down a bit, but if any unit deserves to be the best AA it probably should be the quad, or maybe the bofors...