To be fair, it is one form of centralization; although, I admit, I was twisting the meaning of the term a bit to fit my sarcastic remark.
That being said, as primarily a shitposting lurker who only occasionally actually creates content designed for sharing, I don't mind the extra communities. I'm no stranger to seeing reposts, and I get my kicks from leaving the odd comment that may or may not spawn some sort of rant (usually from myself, not the other parties), but hopefully just tickles someone, and then scrolling to the next. If it's the same thing, I just keep scrollin'.
I could see how it would be irritating to post to multiple communities designed around the same idea, but perhaps the solution is more like turning each community into an aggregate of all similar communities. You could opt your community into a master community, and any post made in one would get shared to all of them.
Ye