The prohibition exists because I wrote the original site proposal that way, and it carried on through to the first on-topic list in the Help Center. Admittedly, you will find little to no mention of gambling or wagering at the Area 51 definition page for this site as no example off-topic questions related to gambling appear to have been submitted, that I can tell.
Before/when Area 51 was being introduced as the formal Stack Exchange 2.0 site creation mechanism, Stack Exchange had asked people interested in creating a new Stack Exchange site, in particular for us existing Stack Exchange 1.0 site owners interested in migrating, to post a proposal to the then-meta.stackexchange.com site.
While this is the original link to my proposal, it is no longer there since the site reset. However, I did find an archived copy at the Internet Archive Wayback Machine. I'll reproduce below.
Quoting myself from six or so years ago:
This proposal is for a personal finance and money StackExchange
site. This is also a proposal to bring an existing SE 1.0
site, Basically Money, into the StackExchange
2.0 network.
Topic
A site to ask any questions about personal finance or money from an
individual or consumer perspective: saving money, spending money,
cutting custs, investing, retirement, borrowing, taxes, interest
rates, insurance, credit ratings and history, etc.
While personal finance can be a localized subject (e.g.
U.S. tax rules, Canadian retirement plan specifics, British government
pensions) there is a lot more that can be discussed across geographic
boundaries, so the site will support both geography-neutral
as well as geography-specific questions through tagging.
(Consider how Stack Overflow enables a Java developer to answer a C#
developer's question about algorithms or patterns. Similarly, Brits,
Americans, and Canadians could answer each other's questions about
saving money, debt avoidance strategies, and so on.)
Target Audience
Average working people looking to attain financial
literacy and find ways to save their money, minimize their taxes
(legitimately), invest their savings wisely, plan for their childrens'
education savings, plan for their retirement, etc.
Already financially-savvy individuals and do-it-yourself
investors.
Financial planning professionals such as
Certified Financial Planners, or others in the personal and household
finance industry e.g. mortgage brokers, personal bankers, debt
counselors, etc. whose goal it is to assist individuals / consumers
with financial planning, products, or services.
[What other major groups may be interested?]
Disallowed Topics
Extended discussion or recommendations for/against
individual stocks. i.e. no "buy" or "sell" recommendations.
While it would be on-topic to ask questions about technicals or
fundamentals using a specific stock as an example, the site
doesn't intend to be another "stock board".
Gambling, lotteries, games of chance, wagers,
betting – except it is permitted to discuss the
taxation or investing of proceeds from such (legal) activities.
However, I suggest that gambling ought to have its own StackExchange
site, if somebody is interested in proposing one.
Advanced economics. However, economics from
an undergraduate or layperson perspective is on-topic, e.g. to help
people understand basic concepts of supply/demand, interest rate
policy, etc. that affect consumers directly. I suggest that, like
Math Overflow for math, a separate site for advanced economics is a good
idea.
Advanced personal tax topics or tax
for business. However, tax questions that commonly come up
from a personal perspective are on-topic. I suggest that a
separate site for advanced tax queries is a good idea.
Advanced or pro finance / trading – e.g.
in forex, commodities, futures, options, swaps as typically practiced
by professionals / dedicated day traders and not by individuals. I
suggest that a separate site for advanced finance and/or trading
topics is a good idea.
Questions
promoting or describing how to do illegal or borderline illegal
activities such as money laundering, smuggling currency,
counterfeiting, income tax evasion, fraud, etc.
[What else should be off-topic?]
Good Questions
- What is value investing? What are the key principles of
value investing?
- I just moved to the United States. What should I do to
develop a good credit rating, fast?
- Are bank customers allowed to provide username &
password to sites like Mint.com?
- It is legal for a retailer/store or other business to
refuse $50 & $100 bills or other legal tender?
- What can I replace Microsoft Money with, now that MS
has abandoned it?
- What is the difference between “good debt” vs. “bad
debt”?
Bad Questions
- [I'll come back and fill in some good "bad question"
examples later.]
Thank You!
If you support the concept of this proposal, please up-vote and
voice your support. I appreciate any and all feedback, comments,
etc.
(It is interesting to see how the actual site definition has evolved over time; while some of what is above remains true for Money, some doesn't. The example "good questions" in my proposal aren't necessarily so, today.)
UPDATE:
I'll add that, at that time many years ago when we were invited to submit a preliminary site proposal for a Stack Exchange 2.0 community, one of the guidelines was specifically to outline questions that ought to be considered off-topic, because one of the problems that existing Stack Exchange 1.0 sites were suffering from was lack of definition and a free-for-all approach to what might be considered on-topic.
And so I had thought to exclude questions about gambling/lotteries/etc. except insofar as those questions have an impact on one's personal finance. The intent wasn't to exclude all gambling/lottery questions, just ones that were about game mechanics, rules, etc. and had no component involving or affecting personal finance (taxes, losses, etc.) So, IMHO, the way this question was rephrased has made it on-topic.
