My wife hesitates to try cooperative multi-player games because she does want groups depending on her to do something she does not know how to do. If your tank does not know her job, you wipe. If this is your crowd controller’s first time in a complicated fight, you may be in serious trouble. This worked fine in City of Heroes: not only could she solo for almost everything, but when she did group, she was a Scrapper who did not care about dying. There are very few cases in CoH where anyone cares if the Scrapper dies or has less than the perfect DPS setup.
As I am learning Team Fortress 2, I see that, but there is another factor: many of the people shooting me already know what to do. There are nine classes to learn, most with some special feature, six of whom have three additional options for their equipment; there are also all the maps to learn, some with multiple stages, all with their scattered refills, control points, backdoors, ambush spots, ramps, etc. While you are trying to get the swing of all this, one guy is lobbing pipe bombs at you, and you will be shot in the head in you pause in a sniper’s field of vision.
Some things are more intuitive than others. Protect this point, check. Move the cart along that line, check. And then you find that the map has multiple vertical levels, a little room with ammo and health, back stairs that everyone else on your team seems to know, and windows that you may or may not be able to shoot through. While someone with a flamethrower is leaping around the corner at you.
One of the great barriers for PvP games is that they are not newbie friendly. If veteran players are alongside green recruits, that is great for training the new guys and integrating them, and horrible for having their first night of play involve being shot in the head twenty times by guys they never saw. TF2 is kind enough to give you a picture of your killer, so you can see where those snipers are after someone kills you.