Nah, a few lead sheets and/or fake books and some practice...you can play tons of songs and sound pretty good. That's what the styles are for.

Of course that's not like writing your own music.

A lot of us home players (probably 90% of arranger sales) came from 2 or 3 manual home organs, with pedal boards and not a lot of style type things...mostly what we called drum machines...with a little percussion added in as needed.

Of course the better musician you are the better the performances.....