I haven't dug into all the sources, but I think there's a potential confounder here, or maybe even reverse causality. The author seems to assume causation when the studies only indicate correlation. E.g. the first link says "chronic loneliness increases mortality risk" but the actual source says "actual and perceived social isolation are both associated with increased risk for early mortality". So for example, it's p…
We cannot explore the possibilities of truth if we do that, but I can appreciate the due diligence. It’s a tricky subject, but life experience informs many of us that there is something more going on than “I materially feel like shit”.
There is a taboo element to loneliness that isn’t often discussed, and that is “I feel hurt that I can be left alone, or that anyone can be left alone or isolated”. So, while the source of the isolation could be material, the feeling that manifests from it is an actual hurt that one feels from the actual thing (isolation). For example, we may be killing our elders when we isolate them in care facilities.
I can’t say if we have the sense as a society to accept data that suggests this pain can be linked to mortality. Isolation in itself isn’t the killer, it’s the pain of “well how could any society leave anyone alone”, and such a phenomenon can be witnessed in the macro outside of yourself (how can we leave people on the street? Etc).
Loneliness and isolation is often in sequence, after abandonment, or negligence, or unforgivingness (if the person “deserved” the isolating). A phantom, immeasurable pain. And even more painful, to deny it afterwards.