It seems many people have bad memories of raiding simply because they chose to be a part of a bad group. Sometimes "the best" guild is made up of "the worst" people. The best memories I have are with laid back, mostly older than me, working adults who were also serious about their game.
I didn't have to deal with any of the drama, the crap, the immaturity, just people who came online, were friendly, about their business, and got the content done. "Good night, love you, see you tomorrow." My kind of deal.
Others want the people who are always in vent, always joking and talking, lots of closeness. That's cool too.
Often though the "top guilds" are cut throat places. Lots of drama. Lots of politics. People come away from those environments often jaded and worn out, and that colors their view of "raiding" as a whole.
In reality, a wide spectrum of people "raid" in these games. From high schoolers to retired folks. Guys to girls. Jerks to wonderful people. Low skill to high skill.
It's about finding a group that is right for you.