I believe great world building comes from events that happening outside of MC reach. If the world is MC centered it makes bad worldbuilding. Also, i think, when some major players make move that will eventually will involve the MC, this is also good sight of World Building, but that only works if this "actions" happens not in the one arc and then MC and this major player will be separated again.
For me good example of good worldbuilding without mention OP is Hunter x Hunter. For example Kurapika didn't follow the MC, also many events in the Ants Arc happened without MC, for example Gon never have met the King.
While I can mention bad example of worldbuilding. For me bad worldbuilding happened in DBZ after the Freeza arc. For me it didn't make any sence that Red Army scientist whose invetions losed to kid Goku, was able to create something that could be even more scary then Freeza.