Did you read the article? He specifically says: "Most important, the application gave me a few starting points. Of those, I still had to consider the team dynamics, existing teams, personalities, seniority, potential, personal situation, future needs, …"

And totally missed on the friendship angle. So, here is my prediction: the people that got fired will find new places to work at where the management is a bit more mature, and will then pull their capable buddies left behind at their old company with them. That's how it usually goes when a new junior manager goes to town with an axe.

Isn't the friendship angle precisely addressed by "team dynamics", "personalities", and "personal situation" ?

Friendships can transcend teams, personalities are not going to be modeled in software and 'personal situation' is a great way to accidentally make a bad situation worse, for instance: by deciding to keep someone who has a family in favor of someone who does not but who is instrumental to the company in non-obvious ways.

So no, I don't see that particular part addressed well or even at all through those three sets of keywords and I've seen companies be utterly destroyed because they fired a guy they thought wasn't contributing enough who just happened to be the glue holding the whole thing together.

This is not a software problem, and it can't be approached with the same toolset that you would use to figure out register optimization, it is first and foremost a people problem. The OP is seriously out of their depth and too full of themselves due to their recent promotion to realize this.

That realization won't be long in the coming though, I predict that within six months there will be another blog post about how he left this toxic company behind to go somewhere else without realizing that he was part of the problem all along.

For reference, I give you his blog post from six months ago:

https://danlebrero.com/2020/06/10/you-dont-believe-in-clean-...

And yet we hire based on people's achievements and previous success. And the world keeps on turning.

It's very hard to build the perfect team from the get-go. However, you can probably build a pretty good team over time. In my opinion, it's better to make an average decision than no decision at all; you can improve from average to something better as you go along.

Yes but what tends to happen is - the risk is - youll probably just end up with a stable team, but not a good team. The best will have left or been pushed out. The ones that stay, desperate enough to be unethical to keep their positions, to lie to cover their asses. A barely functioning but stable entity floating in space not producing anything of value until the company slowly withers and disappears.