It is a distance thing. The closer the range, the more urgent the need for quicker rate of fire (weight, maneuverability, magazine capacity also). Full auto is the maximum you can get. And then it is about being able to deal with recoil. Very close range only.
Bolt action rifles are long range weapons. They get less and less effective until reaching 'practically useless' at room to room fighting distances. Might as well have been a single loader in many circumstances. Think musket
Semi-automatic rifles (full size cartridge still) have a much higher rate of fire, larger magazine capacity (in this case), are fully capable of suppressive fire (not really very effective with one guy with a bolt action). And most of all, at close distances they allow the rapid fire required to score hit(s) and hopefully take down the enemy before he does so to you. Accuracy and power is pretty much the same as bolt action rifles. Reliability is not however.
Assault rifles are next. Much larger magazine capacity, smaller, less recoil, lighter, carry MUCH more spare ammo for the same weight, easier to maneuver, can hit and kill stuff almost as good as the semi auto battle rifles at medium range (hundreds of meters) while being almost as awesome as SMGs down to room to room fighting range.
Then there is the SMG. Needless to say it has enormous ammo capacity, rate of fire and easily controllable, while easy to throw around. Bad at medium range and useless at long range.
Then, pistols. Pretty good at very close range (nothing like SMG however), then bad at short range, useless at anything beyond that.
If you are carrying a bolt action rifle, try to stay the hell away from close range fighting. There's no superiority to be had there. And since RO2 doesn't model reliability & jams at all (that really sucks) there isn't really any benefit over the semi autos at longer range either. Only thing it really does for you is stop you from making the untrained mistake of drawing attention to yourself that rapid fire brings. Blinking muzzle flashes with repeated noise is hard to miss

In this way, it is a good marksmanship training tool.