When I was an architect for startups between 2016-2020 doing mostly green field development using new to the company AWS technologies, I made damn sure that any knowledge was disseminated so I could both take a vacation without being interrupted and I could “put myself out of a job”.

I considered it a success when I realized a company doesn’t need me anymore and I can move on and talk about what I did at my next interview in STAR format.

Agree, and also, promotion is hard if you are too tied to a specific system. Diagonal cross-department promotion becomes especially hard if you are a single point of failure.

But a Bus Factor of 1 has always been considered high risk. Sometimes companies take the risk, but that's a different issue.

This is precisely why the term "Bus Factor" was invented: to point out when it's 1, because it's both high risk to the company and unfair to the dev that cannot go on vacation or extended time off.