One thing is for certain: Internet consumers are fickle.

In 2007, MySpace was on its way to becoming the greatest thing since sliced bread. The company -- originally owned by Intermix Media and purchased by News Corp. (Nasdaq: NWS) in 2005 for $580 million -- boasted 70 million unique visitors a month and, according to eMarketer, perhaps as much as $600 million in revenue derived from ads at its peak.

Flash forward to today, and MySpace generates perhaps one-third of the revenue it once did. Subscriber growth has turned into a slow burn rate, and Facebook has not only eclipsed MySpace in terms of cumulative users but has effectively stomped the service into oblivion.

The question has been posed plenty of times: "What really killed MySpace?" There's never really been a compelling answer, but I think there were three faux pas that may have contributed to its demise.

1. News Corp. didn't understand MySpace's user base
One of the most basic but often overlooked possibilities of what really killed MySpace is News Corp. itself. Rupert Murdoch is accustomed to being king of the hill, but his company didn't know the first thing about running a social-media website. Catering to the television audience and getting users to stay on your website are two completely different ventures. Murdoch took them as just one.

2. Users had too much control
It's my contention that Facebook is able to maintain steady subscriber growth while MySpace fell to the wayside because of the way in which each site handles its user base. Facebook does allow the individuality of its users to be apparent on their profiles, but users are limited to one platform and one page design. MySpace allowed nearly limitless user customization, which created hundreds, perhaps even thousands, of platforms, making the site at some points impossible to navigate. Without one cohesive image, users quickly lost interest in MySpace.

3. Little to no barrier to entry
One factor working against all social-media websites is the relatively low barrier to entry. As long as you have the starting capital, you can have a social-media website. Google (Nasdaq: GOOG) announced its intentions to enter the social-media fray this week, while countless others, including Renren (NYSE: RENN) and Quepasa (AMEX: QPSA), have been around for years. Facebook's success will only translate into a greater amount of social-media startups -- and probably more companies that go the way of MySpace and Friendster.

Whether one or all of these factors contributed to MySpace's demise is irrelevant now, with the company being sold this week for a measly $35 million to advertising network Specific Media. We'll see whether Specific Media can turn this former social-media giant around, but history has shown that once a media outlet falls out of favor, it's very unlikely to be mainstream ever again.

Do you think Facebook can avoid MySpace's mistakes? Share your thoughts in the comments section below and consider adding social-media upstarts Quepasa and Renren to your watchlist to keep up on the latest news in this sector.

Fool contributor Sean Williams has no material interest in any companies mentioned in this article. You can follow him on CAPS under the screen name TMFUltraLong. The Motley Fool owns, and Motley Fool newsletter services have recommended buying, shares of Google. Try any of our Foolish newsletter services free for 30 days. We Fools don't all hold the same opinions, but we all believe that considering a diverse range of insights makes us better investors. The Motley Fool has a disclosure policy that makes you want to click the "like" button over and over.