We live in the world of supply & demand
I find things people want (that already exist)
That they cannot easily find
Then help them find it fast
Save other people's TIME & you win
This is the foundation stone of successful SEO
If you are trying to rank on Google
It surely make sense to follow Google guidelines
I have my SEO list, most of it from the Google Search Central site
Then my job is just labeling and signposting
Just SEO, for now
I think you are right. If you offer products that are difficult but possible to find, then you can make enough money. Nobody wants to bother looking for something, but you can find it and sell it.