By "They were just in-sufficiently cautious legally, possibly un-surprising given Carmack's prior history in founding Id software" you mean the story of how Carmack left SoftDisk and did work for Apogee (on Softdisk computers after hours using a key technique he developed at SoftDisk) and started Id (https://en.wikipedia.org/wiki/Id_Software#History)?

Thanks for mentioning that; I had forgotten that little nugget of history -- it does show this wasn't Carmack's first rodeo at this kind of employer/tech transition.

I had not read until browsing wikipedia just now that the the adaptive tile refresh technique at issue back in that transition was first implemented in a game called "Dangerous Dave in Copyright Infringement". (source: https://en.wikipedia.org/wiki/Adaptive_tile_refresh ) That's an ironic game title for ya given all that has followed!