Lisp machines were clearly abandoned because of their price. Every time I find some history about someone that actually made that decision, the reasoning was exactly alike, those machines costed more to keep than the Unix ones to install, and were less capable due to outdated hardware.
Yet the essay goes all over the place, citing time to market (that was completely irrelevant, UNIX was the newcomer, Lisp machines were there already), university-based prejudice (yet every single one decided the same at around the same time), and blaming the user. The essay doesn't even talk about money.
It would probably help you to understand the essay if you knew that it was written by Richard P. Gabriel, the head of Lucid, the leading competitor to Lisp machines. His company's product was a Lisp system that ran on Unix machines. What he's personally best known for (aside from this essay) is showing that smarter Lisp compilers on commodity hardware like a 68020 or a SPARC could deliver performance that first equaled, then exceeded the performance available from custom silicon; the book he published on this subject was so rigorous that many of the tests in it are still used today for judging the performance of implementations of high-level languages such as LuaJIT and V8.
You seem to think he was advocating Lisp machines, scoffing at his essay based on that misconception. But if there was a single person in history who worked hardest to destroy Lisp machines, it was probably RPG.
Yeah, that's more like it. RPG worked a lot to bring sophisticated Lisp to UNIX systems. He worked on bringing a standard OOP system to Lisp (incl. Lisp Machines, where Lucid (and he personally) collaborated with Xerox PARC and Symbolics to develop CLOS as a part of the ANSI Common Lisp standard).
Then he tried to develop and market similar technology in the form of a databased-backed incremental C++ development system for UNIX (called Energize). https://www.youtube.com/watch?v=pQQTScuApWk
He hoped that the market for C++ environments was larger than the shrinking Lisp market and that C++ developers would want an interactive system with integrated code management in an object store. That did not went well.
Reports were that Energize customers were relieved when Lucid folded, because they would then not get a whole new set of compiler bugs to discover every quarter. They had, instead, the bugs they already knew about and had learned to work around.
Lisp Machines anyway raised the standard of quality in CRT monitors. Manufacturing their own monitors has to have contributed substantially to their downfall, but we all benefited in the end. Well, all but them.
Lisp machines were clearly abandoned because of their price. Every time I find some history about someone that actually made that decision, the reasoning was exactly alike, those machines costed more to keep than the Unix ones to install, and were less capable due to outdated hardware.
Yet the essay goes all over the place, citing time to market (that was completely irrelevant, UNIX was the newcomer, Lisp machines were there already), university-based prejudice (yet every single one decided the same at around the same time), and blaming the user. The essay doesn't even talk about money.