The only FPS I play is TF2, and the average player is so clueless it's really sad. It's only fun on a handful of community servers with many regualrs. And even then, at least 80% of the players on the server have to be regs, or the cluelessness and absolute imcompetence of your and/or the enemy team ruins the fun.
I play Medic most of the time and I'm always trying to keep track of everything around me. I can usually tell from experience if it's safe to peak around a corner or if it's time to retreat. But no matter how good you are, as a Medic you are also depending on your team making sure you don't die to Scouts all the time. As OP said, this isn't about DM skills, it's about trying to win and paying attention. If I get attacked by a Scout and my pocket Soldier just can't hit him and I die, I won't complain. At least he tried. But when my pocket doesn't even wonder why my health drops for no apparent reason, doesn't listen to me calling for help, doesn't hear the scattergun shots, etc... Why am I even playing Medic?
And then there is that general behavior. Having too many support classes and not enough attacking classes. Engies building a level 3 sentry nest on last, while the rest of the team is trying to cap mid. A spy having a backstabbing killing spree and nobody hears anything. I used to give people advice, not even in a hateful manner because I know how counterproductive that is, telling them it's better to do this and that. The usual respone is: "Dude, I just wanna have fun." As if I don't want to have fun. As if trying to win can't be fun by definition. I don't see the point. If you don't want to win, play Minecraft.
TF2. Serious business.