When creating bullshit backlink sites for whatever purposes, usually not for actual reading by users, it is a common tactic to link out to non-commercial sites to show authenticity and mask the true backlink/spam purposes of the site.
This has been theorized as being ond of the original reasons wikipedia received heavy backlinks.
It is not necessarily the fault of an SEO strategy of the linked site.
Disavowing is not a worthwhile practice ( at least in recent years)
Herbal supplement review is not a PBN as it is so heavily filled with affiliate links that the backlinks would have no value to any who purchase such things. So in this case, examine.com is being used as the attempt to seem authentic.
The single term.keywords is problematic and likely unavoidably proof that the backlink profile is very manipulated
I scanned in Moz and although I dont agree with the "why" ( nofollow links are uncommon in traditional small websites and blogs, most don't even know what they are, so your ratio is meaningless to me) the anchor keywords could never be accidental, this is very much intentional.
I don't know what previous designs looked like ..but basic opportunities in on page seo are ignored or automated, top level architecture is weak, the index conventions by letter is wasteful/missed opportunity.
Although not a ranking factor ... accessibility is abysmal
In short, there is so much wrong with the document structure, general architecture and even title conventions.. i dont even think looking into backlink profile is necessary yet.
The article mentions reviews by SEO's but doesn't mention whether they paid anyone to point out the obvious flaws.
Content seems strong to me, I dig into the Rogan and Ferris mentioned supplements regularly, this content is better cited than most I run into and certainly better than bb.com / roid world forums that fill this space. So, it's a shame.
Looks like a ton of poor architecture and document structure decisions to me.