I agree with you. There are things that the experts don't want to talk about (because it's too easy) and then there are things that a beginner can explain in a simpler way than an expert.

Staying in a beginners mind is hard once you have spent some time with a technology. It also sometimes offers great points for the experts what could change, because it could be easier or is simply unclear.

Of course there are very simple-minded blogs with practically no content, but there are also simple-minded Github accounts that offer practically nothing. There are CVs for the same purpose. I don't think this has anything to do with blogging per se.