[lordnacho]

Might also have something to do with the explanation size: this Poisson thing is one little thing. With the internet, it's perfectly acceptable to just do a blog post on one little thing.

Previously, if you were to write a textbook or teach a tutorial, you needed to teach a bunch of things.

So in the internet age there's a bunch of fine grained "best explanations" coming from a variety of authors that beats the best that one guy can do across a range of topics.