Let's say I am a datamining company. With only the text data on 4chan, I can get a general idea of what a number of people are interested in, but I can't correlate it with other posts to get a sense of "X likes Y, buys Z, holds political position A about topic B" because all posters are anonymous.
Now let's say I have a deal with the site administrator. He allows me to get the text data of all posts along with the IP address... or a hash of the IP address. All of a sudden I can gain access to analytical data on millions of people on a top 1000 site. I can know what people like by location, etc...
Now, a clever person might say, "oh, well you can't tie this to me personally without subpoenaing my ISP to get my IRL info." To this, the answer is, "who says 4chan is the only site they're datamining from?" You ever find yourself searching for a product on one site, and then finding an ad for it on a totally different site? Your 4chan posts will be providing ammunition for targeted advertisements.
Furthermore, because 4chan will be generating profit based on number of posters, the smart thing for a profiteering Hiro would be "get more newfags." Suddenly 4chan becomes filled with cancer all for the sake of a few extra bucks. Hiro did borrow money to buy this site, did he not?