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historical rationale?

This seems like a useful feature, and I recall wondering myself why
RnRS "cond" had "=>" yet "case" did not.

I suspect the distinction involved reduced-sugar diet: getting the value
of a clause test within "cond" is very hard without "=>", but getting
the key of a "case" form without "=>" is easy.

Also, "cond"'s "=>" is a somewhat unfortunate kind of sugar, as some
syntax transformers that can produce "cond" forms have to specially
handle "=>" identifiers in their input syntax.  Adding "=>" sugar to
"case" would similarly burden some syntax extensions that produce "case"

I'd like to be informed by the original wisdom for why "case" didn't
have a "=>" in the first place.  Does anyone know the RnRS rationale?