This holds true for all kind of content (YouTube, Courses, StackOverflow, Reddit, HackerNews) where a person has no ownership or no monetary interest (or doesn't worship pure altruism) ... At least content creators are urged to keep their content up-to-date, otherwise they would receive bad feedback (and bad SEO scores over time if people don't stay on your website). I could name you lots of articles I have kept up-to-date over the last 3 years (more than I wrote for sure), and I know this doesn't apply to all content creators, but I can tell you that it really matters for your readers and your credibility.

For sure, the easiest thing as a content creator is publishing (almost) ever green content (see web applications article). However, most often you are looking for topics that solve actual problems of your readers (see react testing library article) which often leads to bleeding edge technology which isn't document well yet.

For what it's worth, there will always be companies with money who pay people to write content to support their products (e.g. SaaS). This makes it harder every day for individuals like me to sustain their livelihoods. However, I strongly believe in the long run quality trumps quantity.

In a perfect world, there would be (1) one perfect learning material (e.g. official documentation) and (2) one unified learning style (e.g. text, video, both) for all students. But we are not living in a perfect world and therefore people look for resources outside of the box.