> I never understood why "multiple return values" is a thing anyone should care about.
For the same reason people care about multiple parameters. There's no reason that the data coming out of a function should be in any way more constrained than the data going into the function.
I don't want to be "that guy", but the United States isn't and was never meant to be a democracy. But that doesn't mean it's any sort of tyrany either. It's a system of checks and balances promoting deadlock.
You have a limited-time dictator, a room full of law nerds, and a Congress half of which is democratic, and half of which represents "the states".
The dictator can do whatever he wants - unless the law nerds or Congress disagree. Congress can do whatever it wants - if you can get both halves of it to agree - unless the dictator or the law nerds disagree - but 2/3 of Congress overwrites the dictator and 3/4 overwrites the law nerds. The law nerds can't do much by themselves and are mostly a reactive force, which are supposed to uphold laws written by others (and generally do so in practice, but of course, not always).
This is a system which promotes the government not doing much, and not changing much, under the philosophy that most change is bad change and no change is better than bad change - while still allowing some good change to flow through the system.
In a democracy, on the other hand, the populus generally always wants change, so that's what they get.
I see a lot of people talking about examples, and while having more of them could be good, I think the actual problem with most modern man pages is a lack of clear description of program behaviour.
I am nowhere near old enough to have used an old Unix implementation, but the man pages back in those days just hit different. just compare how the ls man page starts for the GNU and Unix V7 version.
GNU: "List information about the FILEs"
Unix V7: "For each directory argument, ls lists the contents of the directory; for each file argument, ls repeats its name and any other information requested."
The GNU man page's description continues with one sentence on default ordering before getting to the list of arguments. The only mention ls lists diretory contents is in the description of the -d flag (the flag to make it not do that). The GNU man page also goes on in detail avout the time formats supported by the command, but nowhere does it have anything to say about the format of -l info.
Trying to read modern man pages is like trying to read a library documentation where only the parameteres and return values for function are documented, but no description of the function in itself is given.
For the same reason people care about multiple parameters. There's no reason that the data coming out of a function should be in any way more constrained than the data going into the function.