eBay released a series of posts on how they manage their Jenkins installations [0][1][2] (part four is missing).
I think people choose this pattern when:
* engineers implement something cool
* management want engineering content to promote the company/drive recruitment
* the engineers are pressed for time/not professional technical writers
Some bigger companies stagger the context when it's really hefty and makes sense to chunk it up, plus it drives repeat visitors. For smaller companies, the schedule usually slips, and the first post is usually "look how hard this problem is! wow it's really really hard! isn't is amazing that we even tried to fix it? OK see you next time!".