Look at the list of things they said they have open. Divide in half and it's still a lot because that set of running software is very hungry. PostgreSQL, Slack, Docker, Brave, Cursor, and iTerm2 running on my system puts RAM usage at 23.5GB, and yet modern macs have both very good memory compression and also extremely fast swap. Most Mac users will never realize if they've filled RAM entirely with background software.
e.g. using hypothetical numbers: if base MacOS/typical GPU usage requires 4 GB, then the 8GB model would have 4GB available for running apps (but multiplied by memory compression/swap to fast SSD). Whereas the 16GB would have a much more comfortable 12 GB for multi-tasking in that scenario especially with the multiplier effect of compression/fast swap on top.
So it still feels like a bit of an apples to oranges comparison as far as what an 8 GB model could handle in real usage. I have a friend who does light dev work on an M1 Macbook Air so I don't think an average user would have issues on the Neo day to day, but using the 16 GB as a yardstick doesn't seem that useful.
Sure, but, by the numbers I'm seeing, their much heavier load than mine would be waaaay into swap territory for them and is still doing just fine. That's really my point. That's why I think it's actually pretty reasonable to look at half their load and say "man, even half their load is a pretty heavy load for most people, so half their RAM will almost certainly be more than plenty for the target market".
Also, just for the info, my Activity Monitor says that the non-purgeable OS RAM (wired) usage is around 3GB on Tahoe 26.3.
To the major point of can it (Neo 8GB) run multiple programs at the same time, my experience would say it would have no issues doing so given what one can do in 16GB on lesser Mac hardware. (Maybe I am wrong and MacOS takes all 8GB for itself, but that seems far-fetched.)