If there were no measures/time signatures, we would not know how many beats per measure, and therefore we wouldn't be able to "feel the beat". There is a distinct difference between 4/4 and 7/8. If music was without these, people wouldn't really understand how to play the song the same way someone else did. There would not be any unifying concepts.
I would use these answers in conjunction with another's answers. I get what the question is, but I can't really think of how to formulate what I'm saying. Good luck!