Does it really matter, tho?

Another reason it matters is they might have done it differently which could inspire future improvements. :)

I like to read bibliographies for that reason—to read books that inspired the author I’m reading at the time. Same goes for code and research papers!

Some people think it matters to properly learn history, instead of urban myths.

History is one thing, who-did-it-first is often just a way to make a point in faction debates. In the broader picture, it makes little difference IMHO.

Interesting. My experience w/ HP-UX was in the 90s, but this (Integrity Virtual Machines) was released in 2005. I might call out FreeBSD Jails (2000) or Solaris Zones (2005) as an earlier and a more significant case respectively. I appreciate the insight, though, never knew about HP-UX.

https://en.wikipedia.org/wiki/HP_Integrity_Virtual_Machines

HP-UX Vault, released with HP-UX 10.24, in 1996,

https://en.m.wikipedia.org/wiki/HP-UX

What you searched for is an evolution of it.