Usually, in Far Cry games, you are fighting some kind of enemy militia. Far Cry 4 and, if I understand correctly, Far Cry 6 are the exceptions so far, where you fight an actual national military. And at least in Far Cry 4, it’s a disappointingly small difference as compared to the militias and pirates of earlier games. Now, sure, these are the national militaries of tinpot dictatorships, presumably not even regional powers, let alone superpowers with a bottomless backlog of tanks and jets on the bleeding edge of military engineering. You wouldn’t expect them to necessarily have much in the way of nightvision, it’s not super out of place that they communicate mainly via radio signals you can intercept, and it’s fine that the standard issue assault rifle is the AK-47 rather than the AK-74 or tacticool rifles from recent years like 2009’s FN SCAR (the efficacy of things like the FN SCAR over older weapons is debatable – after decades of paying arms manufacturers for new assault rifle designs, the US army has decided to use the M16 forever – but certainly the only armies still using AK-47s are armies who can’t afford AK-74s).
But you would still expect these tinpot dictatorships to have tanks at all. Not to mention IFVs, which are just perfect for video game bad guys. An IFV is essentially a light tank which also carries a squad of infantry into battle, so it’s something you can slap onto your existing infantry squads to upgrade them into a miniboss. And yet, they don’t appear in Far Cry 4. It’s not like Far Cry 4 doesn’t already have vehicles with turrets, so it doesn’t seem like it’s a technology problem.
Tanks have the problem that it’s very difficult even for a supernaturally durable lone attacker to take them out, as modern tanks are basically immune to frontal attacks from most shoulder-mounted anti-tank rockets. There’s plenty of solutions, though. First of all, it’s a Far Cry game, so you can decide to ignore realism and let an RPG-7 blast straight through the front armor of a T-72 for no better reason except that it’s cool. Secondly, when you picture an RPG in your head, you are picturing an RPG-7, and that is a 1959 weapon ineffective against modern tanks. But it’s not like the whole world gave up on anti-tank weapons and just kept using RPG-7 forever. Far Cry 4 has a secret unlockable weapon which, the Wiki tells me, is some Biblical reference because the arms dealer who gives it to you is a Christian zealot, but it looks like an RPG-29, which punched through the front armor of a perfectly modern Challenger 2 in Iraq. But also, third, you could always have tanks be nearly impossible to destroy from the front and have fights against them focus on hitting their weaker top and rear armor.
Instead, Far Cry 4 gives us exactly one new enemy type (not counting wild animals), the hunter. The hunter is a very good addition to the game, a stealthy enemy who doesn’t show up on radar and if you tag them (which normally allows you to see enemies through walls) they only stay tagged for maybe five seconds before becoming untagged, plus they can take control of nearby animals, which are normally hostile to both sides. Hunters plug up a lot of Far Cry 3 enemies’ most consistently exploitable weaknesses (luring in or releasing an animal is way OP, tagging all enemies so you can see them all through walls makes stealth pretty easy and makes you almost impossible to flank), and if Far Cry 4 were about fighting warlord militias or pirates or religious terrorists, that would’ve been fine. But Pagan Min’s army is supposed to be an army, and the absence of any armored vehicles is a disappointment.