Earlier quoted context omitted.
Super annoying, yes! I completely agree with you. It's not just Firefox being the culprit here though... .NET is the same, and so is Chrome, and the list can grow like a mayor's coat-tails! Also, here's a genuine usecase for a truly offline installer... What if you are the "resident software/pc maintainer" of your extended family.... In such a case, would it not make better sense to have one complete download, then c…
The automatic updater takes care of all of the use-cases you mentioned better – why waste time manually copying files around when your relatives could be running the update days before you make it over with that thumb drive? That said, they do make the full installers easily available (google “Firefox offline installer”) should you need to update a ton of computers behind a slow connection.
For sure, lycos/ddg/ask-jeeves/bing "Firefox offline installer" is an option that is not lost on us luddites :).
But did you also notice the parent comment: "Googling for things like "firefox standalone redistributable offline install" are a road to nowhere"? ;)