I think the core is: Human dignity, full agency, right to property, non-aggression

How you defend and narrate these into your political philosophy or day-to-day really differs from person to person, exactly like you said:

Which means that if we respect that this is the case and people can and will disagree with what we ourselves think is the Theory of Everything then it also proves that there is such a thing as the individual and that it may be the smallest denominator when we ignore time (most people tune their philosophies as we experience life.)

However, and I think that this is why I cannot agree with the author: this is not all there is. I haven't seen evidence that there are many libertarians out there that would deny the existence of synergy. It's just that if you respect people's agency, then participating in a synergic scenario is a choice too.

Example: Very early in my career I decided to no longer work for a boss directly because corporate politics were bothering me, a lot, and I felt this (and let's be honest, ceilings) were holding me back. Instead I took on the risk of being an independent contractor. I still worked with companies and also governments because they hired me; I was still part of a larger whole and I've been much more productive in that role than I was as an employee because I was not subjected to politics much. I've benefited from this and - per feedback - so did the larger societal structures I've contributed to.

Therefore I think that attacking all this through a strawman of absolute individualism is weak, because it isn't absolute for any real-life libertarian I know. It's just that in increasingly polarized debate and especially politics, people search for differences more than similarities. Personally, I think the polarization is a nasty signal that people have problems that remain unaddressed for a longer time.

Absolutely! And "past returns are no guarantee of future performance" is no lie outside of the prospectus for some Blackrock fund either - it applies to the output of every soft science; from anthropologists to sociologists to economists to politicians; it's all narrative and it's all a swamp.