Chuck D uses inner rhyme to create flow. Inner rhyme is the rhyme of two parts of a single line. For example, "Listen if you're missin' y'all" has a rhyme between "Listen" and "missin'." One effect of Chuck D using inner rhyme is that the words in the lines become easier to hear, because your ear is drawn to what Chuck D says inside the line rather than to the end of the line. If Chuck D only used rhymes at the end of his lines, you might forget the rest of the line. For a rapper as political and message-oriented as Chuck D, inner rhyme is an important ally.
Consonance and Assonance
"Fight the Power" has a lot of coherence for a song that doesn't really use end rhymes very often. This has to do with Chuck D's use of consonance and assonance to make lines that just sound good together. Consonance is the matching of consonant sounds in words, as in "pumpkin pie." Assonance is the matching of vowel sounds, like in "fly a kite." Check out the first few lines of "Fight the Power:"
1989 the number another summer (get down)
Sound of the funky drummer
The "m" and "n" sounds tie the two lines together more so than the rhyme, even. The matching of "num" "sum" and "drum" with consonance and assonance makes the lines sound like they were made for each other.