[sdsd]

Idk why but even highly knowledgeable people capitalize random tech words. In the Tanenbaum–Torvalds debate, Tanenbaum regularly calls it LINUX (maybe a habit because UNIX is smallcaps'd per the trademark?). Lisp is often called LISP (check Wikiquote for ample examples), although this is forgivable since Lisp really did used to be an all-caps acronym.

[mdp2021]

Typewriters and their intrinsically limited rich-text capabilities encouraged that all-caps use for distinction.

In the case of Unix, it was trademarked as all-caps, for some reason ('Multics' was not) - so for Linux it may have seemed to follow for consistence.

[sdsd]

According to Dennis Ritchie from the Jargon File:

"Some people are confused over whether this word is appropriately ‘UNIX’ or ‘Unix’; both forms are common, and used interchangeably. Dennis Ritchie says that the ‘UNIX’ spelling originally happened in CACM's 1974 paper The UNIX Time-Sharing System because “we had a new typesetter and troff had just been invented and we were intoxicated by being able to produce small caps.” Later, dmr tried to get the spelling changed to ‘Unix’ in a couple of Bell Labs papers, on the grounds that the word is not acronymic. He failed, and eventually (his words) “wimped out” on the issue. So, while the trademark today is ‘UNIX’, both capitalizations are grounded in ancient usage; the Jargon File uses ‘Unix’ in deference to dmr's wishes.

Source: http://catb.org/jargon/html/U/Unix.html

[benj111]

Plus, early programming seems to have been all upper case.

It wouldn't be surprising to me if people just conflated programming with upper case, and by extension the names used.