Ok after reading the entire thread (again), reading FFF #282, FFF #258 and the wiki article on world generation, it appears that vanilla factorio does not and has never scaled ore size with distance from starting area.

That becomes clear if you look at the mechanics ( https://wiki.factorio.com ...

Well for me the main point of RSO is that the ressources get larger/richer the farther one moves away from the starting area. Vanilla doesn't do that even in 0.17, does it?

So of course we still need RSO!