"Interlisp is a very large software system and large software systems are not easy to construct. Interlisp-D has on the order of 17,000 lines of Lisp code, 6,000 lines of Bcpl, and 4,000 lines of microcode."
So large. :)
http://www.softwarepreservation.net/projects/LISP/interlisp-...
Consider this: at any moment in history, the prevailing state the art in computing and information systems are characterized has huge, very large, massive, etc. Some years later, it's a portable device with a battery, and we forgive and snicker at those naïve souls that had no idea at the time.
It's still true today. Whatever thing you have in mind: vast software systems running clouds, megawatt powered NVidia GPU clusters, mighty LLMs... given 10-20 years, the equivalent will be an ad subsidized toy you'll impulse purchase on Black Friday.
You're instinct will be to reject this as absurd. Keep in mind, that is the same impulse experienced by those that came before us.