So what rhyming poems do is they take all these nearby sound curves and remind you that they first existed that way in your brain. Before they meant something specific, they had a shape and a way of being said. And now, yes, gloom and broom are floating fifty miles away from each other in you mind because they refer to different notions, but they're cheek-by-jowl as far as your tongue is concerned. And that's what a poem does. Poems match sounds up the way you matched them when you were a tiny kid, using that detachable front phoneme.