"And isn't the premise of this thread that the "install" would be deriving the bulk of its files from a backup volume? (e.g., Time Machine)."

I guess, not. Lots of people do not use Time Machine. The premises were: 1. problems with dial-up customers (file too big to download); 2 (related). The real installer missing on Macs with pre-installed Lion, making it impossible to create a bootable Lion disk without going back to downloads.
For the first one, I will see but I doubt it (the installer size is much less than the original one)


Alex
3.1 GHz 13" MacBook Pro 2015, 8 GB RAM, OS 10.11.2, Office 2011, TimeWarner Cable
2.8 GHz Xeon Mac Pro 2010, 16 GB RAM, OS 10.11.2, Office 2011, LAN