I guess on your wish. Anyway nobody cannot prevent you use them in your RP. I for example did expedition for founding ex-Cayman, where left one my pob. And i even found it. Just systems itself havent anything useful, only small number contain any solars except sun, and even them rarely have any interesting objects. (for example ex-O9 havent anything interest, while basically normal system).
They exist inRP. The only limitation was that actions within Uncharted I and Uncharted II, back then, weren't allowed to cause repercussions outside these systems. Luckily, this was later changed. Uncharted II (Narcrahtite) is still out there. Uncharted I is different now and Uncharted Kusari might still be out there and accessible through Shikoku. Uncharted Liberty and Uncharted Rheinland are currently not accessible anymore, except via blind jump or singleplayer commands.