The example on the linked video it isn't, correct.

Here is another video, this time with S-PACKAGE used to develop Nintendo 64.

https://www.youtube.com/watch?v=gV5obrYaogU

Which given the REPL capabilities, you can easily embedd them on it, just like the other video.

It's also from 2013

It is when you use a CRT instead of a flat panel.

that's a poorly chosen counter-complaint. before SGI, symbolics owned the market for 3d graphics. this was a world where you could also just do (create-window), see the window, and get back a handle you could use to draw in it. starting with X10 afterwards for me was like drowning in mud.