I think portraying it as a fight to the death is more interesting. This is why any new phone is "an iPhone killer" rather than a phone attempting to get some market share.
Think this is more accurate. Maybe they can't exist post growth because in the social media space we have obvious reference to companies like MySpace and Friendster. Where the slow down of growth happened due to competitors that will chip away users/market share until the product becomes largely irrelevant compared to what it once was. In this situation investors are looking to get out for as good as price as possible.