How is "following back" each of the 20,000 people that follow a corporate or prominent blogger account on twitter a legitimate use? Nobody can read that firehos

How is "following back" each of the 20,000 people that follow a corporate or prominent blogger account on twitter a legitimate use? Nobody can read that firehose. It seems like people are overloading the "following" feature --rather than a subscription to the user's content, instead people are using it like a "karma" vote. Maybe they need to separate the two.