Kev's quote:
Welcome to Stack Overflow! Whilst this may theoretically answer the question, we would like you to include the essential parts of the linked article in your answer, and provide the link for reference. Failing to do that leaves the answer at risk from link rot.
The guidelines on what constitutes a great answer were determined based on lots of trial, error, and growing pains that the StackOverflow community faced, as well as what the founders observed happening to other traditional forums on the Internet.
Posts with links might be valuable to the original poster, but that value is only temporary. StackOverflow's goal is to improve the Internet as a resource of knowledge and provide lasting value for years to come.
Have you ever spent time Googling for an answer, wading through noisy forum posts, only to discover that a link posted, filled with promises of holding the solution, ended up displaying nothing but 404 in your browser? What did you gain from that broken link?
We realize that the Internet, while a great resource, is constantly changing. Links break, and the community recognizes this fact and agreed on certain guidelines to prevent clutter.
We don't want you, or anyone, to spend valuable time searching for a solution, finding a question related to the topic, and then only find that it has rotten, broken links of no value. Instead, we want you to still benefit from our community, even if the rest of the Internet is inherently unstable.
In summary, this guideline exists just as much for your benefit as it does the benefit of the people who will read your answer 6 months, 1 year, or 5 years from now.
The goal of StackOverflow is to act as a resource not just for the original poster, but for others who have that same problem and seek answers. Spend some time on the site looking at questions and answers. Get to know the platform, and you may open your eyes.
In fact, many users on this platform started out with your same skepticism, and today, those same users are making comments very similar to the one Kev left for you, politely welcoming new users to our community while also keeping this site strictly focused on great, quality content.