I mean when someone's motivation comes from what they themselves are interested in and their wanting to pass along their knowledge to help others, as opposed to say the external incentive of being financially compensated. I know this seems completely foreign in this age of played out incentives, but such publishing used to be quite common before independent sites were drowned out by webspam. You'd do a search, dig through a few pages of results, and hit upon an information-dense (likely plain text) site of someone thoroughly geeking out about your topic.