This is so incredibly useful! I also remember it from those days as a kid. I wish I knew it was still a thing all this time!

I think it originated with the Lisa. It's mentioned in that context on folklore.org (1):

> Lisa users never dealt with Lisa applications directly (these were called tools in Lisa parlance) but instead always manipulated stationery pads which produced documents.

(1) https://www.folklore.org/ProjectView.py?project=Macintosh&in...

It's been there for a very long time. I used to teach DTP with QuarkExpress back in 92 and this feature was gold. It helped to preserve and not destroy the page templates of the magazine. The fine folks at this publisher had a hard time adjusting to the new world and it saved me so much time when they messed around with the layout and page settings