How do rhyme schemes help poems?
Flow and rhythm.
Rhyme is often used to give a poem an easy flow and rhythm.
This rhythm can just be for the enjoyment of the reader however it also can be interpreted to be lots of different things, for example if it is a poem about conflict then it could represent gun shots or the marching of an army.
Hundreds of years ago, poems and songs were not written down so poems from those times will often rhyme so they can be remembered and shared with others, however I do not believe this is relevant to your question!