[jerrre]

At the risk of being nitpicky:

Updating tools in your environment/workflow is exactly a thing that can lose a lot of time, often for not much gain[1]. One way to become very productive is to know your tools very well, and that would extend to not changing them often.

[1] not much gain in productivity, but perhaps in security, compatibility, etc

[alpanka]

You are ignoring that we often use software created by other people.

Raise your hand if you have ever spend an afternoon trying to get someone else's build scripts working. Wondering why make, cmake, scones and ninja are used in the same project...

[calvinmorrison]

There you nailed it. Want a feature X in the plan9 kernel? Okay, add it. Recompile and Run. When a system is self contained and has fewer external users it's easy to iterate and develop without the fear of breakage