Answer:
Only the poems with a specific rhyme scheme need to rhyme,
Examples - Limerick's, Sonnets, Assigned Rhyme Scheme poetry,
Some poetry does not need to rhyme,
Examples - Haiku, Free verse poetry,
The reason some do not need to rhyme is because they have an assigned syllable count. Which makes them flow in a different way. Although, most poems need to have specific syllables, but do not need to be exact.