This is correct. It's because, basically definitionally, the amount of people who have deeply engaged with any topic is very low compared to the number of people who have shallowly engaged with it. This means that the amount of reference material written by people with deep understanding will be much much less than the amount of reference material written by people with shallow understanding.
"Back in the day", this problem was addressed by having significant hurdles in order to publish material on a topic. E.g., books used to be the primary way to learn about a topic, and in order to publish a book you must 1) deeply engage with the material for quite a while simply to write the book and 2) become fairly credentialed / convince a publisher you're worth their time, etc. Same thing with academic papers.
The internet has completely removed all barriers to publishing, meaning it's up to us to sort the wheat from the chaff.
"Back in the day", this problem was addressed by having significant hurdles in order to publish material on a topic. E.g., books used to be the primary way to learn about a topic, and in order to publish a book you must 1) deeply engage with the material for quite a while simply to write the book and 2) become fairly credentialed / convince a publisher you're worth their time, etc. Same thing with academic papers.
The internet has completely removed all barriers to publishing, meaning it's up to us to sort the wheat from the chaff.