I completely agree that it is not conclusive proof, but it's not completely irrelevant either. I guess my usability / user-centric design hat is showing :-)

The fact that novices expect there to be an elseunless, or (to pick another example) expect length to work on arrays and hashes, are evidence that there is confusion.

In some instances the confusion is due to misconceptions and missing knowledge (e.g. when people try to use symbolic references instead of a hash or something equally useful).

In other cases it can point to lack of orthagonality, or possibly sub-optimal choice of names (would life be easier if length was called strlength or something similar?).

The fact that something is often asked about or requested may well be a clue (not proof :-) that there is a problem that needs to be addressed.