What purpose does this serve? Maybe you could explain to me why someone would do this? What is the benefit of using several different domains instead of subdomains or subfolders on the general site?
A couple days later, Bob wants to go there to check out another Star Wars question. All Bob remembers is "starwars", and fails to find the site.
Compare to "Hey Bob! I found the answer to that Star Wars question we were discussing at lunch yesterday on this great site, starwarsanswers.com".
A couple days later, Bob wants to go there to check out another Star Wars question. Bob has a good chance of remembering "starwarsanswers".
Separate domains for different topics is more friendly to users. That's probably why Google has no problem with it--as the Google guy said, its impact on users they care about.
http://www.starwarsanswers.com/travel-how-tos http://www.starwarsanswers.com/language-how-tos http://www.starwarsanswers.com/health-how-tos http://www.starwarsanswers.com/home-garden-how-tos http://www.starwarsanswers.com/wedding-how-tos http://www.starwarsanswers.com/dance-how-tos http://www.starwarsanswers.com/black-belt-test http://www.starwarsanswers.com/mahalo-profile
How do you navigate to these pages from the starwarsanswers.com homepage? I don't see any of those listed on the right hand margin. Sure, they may have been exposed because of a deployment error early on that has now been fixed.
Looks to be a basic website error than something attributable to malice.
Also it's better for advertisers.
It's a good idea. There's nothing wrong with what Mahalo is doing here.
The specialized domain/community allows users to get into much more detailed discussions about their topics and it helps filter out contributors with just a passing interest. This increases the reliability of the information shared and the quality of the discussions.