I hate the fact that Papa Doc didnt rap at the end

Hahaha that is right and you are a test tube baby haha haha go kill yourself nerd

I think the point was to illustrate that Papa Doc was only a poser who had rehearsed his lines beforehand, and couldn't battle off the bat. When Cheddar asked Rabbit if he was afraid that Papa Doc was going to use all the things that had happened to Rabbit and his gang, Rabbit knew that's exactly what would happen - and so he was able to flip everything around to his benefit. If Papa Doc had been able to use Rabbit's background, his girl and Jimmy against him, Rabbit would've been crushed realistically. At least it wouldn't have been a clear cut victory.

It made the last rap battle that much tighter. Rabbit had so much *beep* on him it made him choke. Completely. He couldn't even defend his title. Like stated before his rhymes were rehearsed. A real rap battle artist can handle any and all situations. Poppa Doc was a fraud. Besides having Rabbit go first took away any cracks Poppa Doc had on him. He had nothing to rag on after that. Rabbit took that power away and shoved it in his face.

those comments about Papa Doc's lines all being pre-rehearsed - I hadn't even thought about that but yeah - they only time we see him rap is at the beginning and most of his stuff sounds generic or pre-prepared - the only thing vaguely improvised/relevant-to-his-opponent was about him looking like Cris-Cros even though he didn't look that much like them.
So as stated above, when MC Bob mentions it, Rabbit realises that he'll have some pre-written (either by himself or maybe even by other members of Free World) lines about him and wont be able to deviate from it, so just goes first and pre-empts it all.
But even if he'd mis-judged it and Papa Doc was able to ad-lib some new stuff, the knockout blow was Cranbrook. If he'd just dissed his appearance or clothes or whatever, maybe Papa could have tried to come up with something to flip it on him, but exposing him as a fraud to the entire shelter - there's no coming back from that.
And I love how "his real name's Clarence" gets a bigger reaction from the audience - and from Papa Doc himself - than the Cranbook reveal ha ha!

It wasn’t just that Eminem had said everything he had to say. It was also how the crowd got so worked up and was already 100% behind Rabbit. Before Papa Doc even said “Ay-yo,” the crowd was rowdy and screaming “What! What! What!” … the crowd reaction might’ve helped make Papa Doc shook

it would have been even more anti-climactic if he just threw out a mediocore rap to end the movie on. Instead, the note we are left on is Rabbit's clever adaptation to a situation as well as what he knows about the guy.