True, but that'd be very esoteric - a string input field that only accepts values from a dictionary. Although also if the input space was only these values but the input size was infinite you'd have a similar issue :P
It'd be esoteric for a system to enforce only containing values from a dictionary, but every sentence ever spoken by anyone alive fits in a 64-bit space by a wide margin. For real-world input you could still reverse most passwords uniquely given enough time.
It's actually kind of a fun problem -- the fewer bits you have in your hash the easier it is to find _any_ collision that gives access to the current system, but the harder it is to uniquely reverse the hash into a plausible password for stuffing into other systems.
