Some people are really passionate about earning money. But indeed I feel that for this to work you need to be passionate about a topic, and also about monetizing it, which is not everyone
The fallacy of this type of advice is that marketing a certain activity, in this case a blog, is a full-time job in itself.
> This is the quickest way to [...] create a sustainable additional income.
The entire blog post starts with essentially a lie. The following requirement:
4. Back-link building
> This is tedious work. Cold emailing, constant reminders and
> outreach and content creation. This person would focus
> entirely on growing your backlinks by creating
> viral/shareable content and reaching out to partners who
> might want to link to your site.
is all but "additional" income.
It reminds me of that famous guy, let's call Tim Ferrous for anonymity, who advertised the dream of a 4-hours workweek, while working himself 24/7 in order to market himself and selling his products. Not counting the fake website(s) and fake reviews he's commissioned as part of his marketing.