Basically you have a simple algorithm where a computer is trying to "know" 10M+ people and figure out how to "trust" (and indicate to others how much they can "trust") that person.

You get the [reputation system](https://meta.stackexchange.com/questions/7237/how-does-reputation-work)

The presumption in awarding +5 rep for upvoted questions, and 2× that (+10 rep) for upvoted answers is that __people who supply good answers are _2x more trustworthy___ to the site.

A person supplying a good answer is demonstrating 2× the subject matter knowledge per vote "useful" as far as the site is concerned than a person supplying a good question. This may or may not be accurate about the users, but to the site's simple algorithm it is not a bad mechanic to guess.