Well, take a look at the dates of when Postgres was created and when SSDs become available. Better, find articles about internal algorithms, B-trees, times of operations like seeks etc. The Postgres was initially written with disk operation timings in mind, and the point is that's changing - and I haven't heard of Postgres architecture changing with that.
That blog post is very light on details can be condensed to a single line/paragraph. LSM trees are more efficient for SSDs and modern databases use them.
I don't know enough to comment yet but will go read about it.