I play on my own quite often.

I see a lot of players in the "No Squad" bracket, from whom I'm getting information fed to me. I also have well-trained scanning skills, and usually run as a Scout, so it's pretty rare for anything but another Scout to get into Shotgun range without me noticing, even when I'm not fitted for scanning. My Logi and Assault builds (on other alts) are less scanning-focused, and unless the other guy screws up, I don't usually see CQC Scouts until too late. And as a Heavy, I need someone watching my back, or I need to constantly be looking around just in case, because if I don't, I die to a sneaky Shotgunner.

I'm not saying they're completely fair and balanced.

I'm saying they're a lot closer to it than you can see, because you're not playing the role correctly, and are complaining that people are outplaying you. There are problems, but the problems you're seeing are more because of your own mistakes than because of flaws in the design.