Because it's easier (and more quickly gratifying) to be a jack of all trades than a master of one.

We're a community with topics described foremost in breadth, secondarily in depth.

A large number of people can bring in general understanding of a variety of topics, a somewhat more specific (if still broad) understanding of the general subject in question, ten minutes of Googling around, and a bit of critical thinking to answer most of our questions. Seriously; scan our questions with a more critical eye at some point. The clear majority (if not all) can be answered with the previous listed "qualifications" (if I can use such a strong term).

Thus the one who answers gets to voice his thoughts, gets his (pretend) expertise commended, and he walks away patting himself on the back for being helpful. Most importantly the answerer can do all of this with both little work previously (collecting life experiences, education, etc), and with little work to answer the question.

Here on WB.SE I can weigh in on economy, politics and governance, military issues, societies, philosophy... and I'm someone with a degree in computers and who works in computers; I'm not an expert in any of these fields yet I can still be helpful. That's a rewarding experience.

Contrast this to me trying to help on Stack Overflow. My degree, profession, and hobbies are/were coding and computers, so it stands to reason that I should find it easier to help there. This is very much not the case. I can spend hours viewing question after question on that site, and only manage to offer a helpful answer if I happen to be the first to answer a question. Most of the questions (that aren't answered correctly in <15 minutes) even in my more specific fields of expertises within Stack Overflow either go beyond my knowledge, or would require significant time to recreate and troubleshoot. So I can't, or don't help with them.

It's easier and more immediately gratifying to answer questions here; you don't have to expend much effort to feel like you genuinely helped someone.

Other considerations

• World building is rich in variety; it's hard to get boring or to burn out. Your mind is challenged to think in different ways.
• No matter how much we try to fight it, many questions end up being deep in opinion, and everyone likes giving their opinion.
• It's hard to challenge incorrect answers. Who's really to say how to prevent the collapse of the Soviet Union? Or about the future tech of automating every job? Or the best way to fit monsters in your pocket? We delve so far into theory that it's difficult to say one answer is wrong or figure out who's more right.
• People like stories. World building as a whole aside, reading answers and writing answers in-and-of-themselves are often like stories as compared to most other SEs.

Because it's easier (and more quickly gratifying) to be a jack of all trades than a master of one.

We're a community with topics described foremost in breadth, secondarily in depth.

A large number of people can bring in general understanding of a variety of topics, a somewhat more specific (if still broad) understanding of the general subject in question, ten minutes of Googling around, and a bit of critical thinking to answer most of our questions. Seriously; scan our questions with a more critical eye at some point. The clear majority (if not all) can be answered with the previous listed "qualifications" (if I can use such a strong term).

Thus the one who answers gets to voice his thoughts, gets his (pretend) expertise commended, and he walks away patting himself on the back for being helpful. Most importantly the answerer can do all of this with both little work previously (collecting life experiences, education, etc), and with little work to answer the question.

Here on WB.SE I can weigh in on economy, politics and governance, military issues, societies, philosophy... and I'm someone with a degree in computers and who works in computers; I'm not an expert in any of these fields yet I can still be helpful. That's a rewarding experience.

Contrast this to me trying to help on Stack Overflow. My degree, profession, and hobbies are/were coding and computers, so it stands to reason that I should find it easier to help there. This is very much not the case. I can spend hours viewing question after question on that site, and only manage to offer a helpful answer if I happen to be the first to answer a question. Most of the questions (that aren't answered correctly in <15 minutes) even in my more specific fields of expertises within Stack Overflow either go beyond my knowledge, or would require significant time to recreate and troubleshoot. So I can't, or don't help with them.

It's easier and more immediately gratifying to answer questions here; you don't have to expend much effort to feel like you genuinely helped someone.

Other considerations

• World building is rich in variety; it's hard to get boring or to burn out. Your mind is challenged to think in different ways.
• No matter how much we try to fight it, many questions end up being deep in opinion, and everyone likes giving their opinion.
• It's hard to challenge incorrect answers. Who's really to say how to prevent the collapse of the Soviet Union? Or about the future tech of automating every job? Or the best way to fit monsters in your pocket? We delve so far into theory that it's difficult to say one answer is wrong or figure out who's more right.
• People like stories. World building as a whole aside, reading answers and writing answers in-and-of-themselves are often like stories as compared to most other SEs.