Jeff King [off-list ref] writes:
Because from the user's perspective --foo={bar,baz,bleep} is about
selecting exactly one of {bar,baz,bleep}.
I do not feel very strongly about this either way, and without any prior
end user "Huh?" input, I would probably have argued like you myself, but
I saw the original message from Miles about giving more than one --date
and getting perplexed to see that it did not work, so...
I am not likely to use --tz=Indian/Christmas myself; GMT and local might
however be useful in some situations, though.