If you can't spit it in real life, you can't do shit with your lyrics. Simple as. An emcees lyrics are an important aspect of his style, but not more so than his flow, voice etc. If you got a dope flow and voice, you can get away with shitty lyrics. If you got no flow and a god-awful voice, all the lyrics in the world can't save you from being wack.
Saying that, text is a great way to improve your lyricism as people judge your work entirely on the lyrics, compared to the audio booth where good lyrics seem like an added bonus.
On
RF, a lot of the text open mic heads write stuff to spit out loud with a catchy flow to it. If your shit is blatantly stretched, it won't get any love from respected writers on here.