The incentives of the Internet of today aren’t aligned with quality. The values here are quantity and velocity.
What this means is that it is beneficial for someone with no fame to write a quick article or record a basic course on something that has been developed for years by someone else.
But it doesn’t stop there. I’ve seen (this is often the case in Medium) people writing articles about the articles of others. Invariably, the “others” are known authors or gurus. The new authors have nothing to add, they just seek fame (or mere credibility) by association. It’s a culture of repackaging.
Worse, something is always lost in the translation. The exercise may be valuable to the writer – after all, we learn best when we write what we learned in our own words – but as far as the net total of internet knowledge goes, it only serves to muddy the waters.
It’s always better to drink straight from the source.