You could be onto something Avenger, but it's also the fact that games do lose exponential amounts of fans after the first few months, if they released everything at once at least the fanatics could enjoy everything the game has to offer before that new car smell wears out.
Life support has nothing to do with sales, if you read the article it's more in regards to how they try to artificially extend it's life by releasing time gated content. It doesn't have to do anything with the popularity of the series, but rather how interest is lost over time in a specific title from the series.