Some people genuinely want to help others, without any immediately visible reward.

I won’t say it’s necessarily altruistic, as of course there could be a drive from inner machinations that we’d never be privy to.

(Sometimes the exposure of an article can be considered a reward, for those looking for ego inflation)

Even myself, I generally don’t leave comments unless I feel they’re going to be helpful or insightful to someone else. But I am also biased, as I do have a very strong affinity towards sharing information, so I greatly appreciate the effort artisans and those more knowledgeable than I go through to share such knowledge.