i presume you're questioning the assertion that it seems like an attempt to effectively centralize the fediverse?

Yes - anyone is free to start an instance.

However, a new instance is not going to get any communities on Piefed's preset list of subscrptions, nor is any community which the Piefed devs, for whatever reason, disapprove of or oppose or simply dislike. And that means that if Piefed can gain enough users (by, for instance, astroturfing the appearance of greater popularity than it in fact currently enjoys), then it will be able to effectively gatekeep the fediverse - to undermine or advance existing instances and create an insurmountable barrier to entry for new instances, by granting or withholding positions on its list of communities to which users are automatically subscribed.

Additionally, it seeks to do essentially the same thing to individual users, by instituting a karma system (something that the rest of the fediverse has not coincidentally avoided, since it was and is so easily and often abused on Reddit) and by automatically collapsing responses with 10 or more downvotes (it would be child's play to use bots to deal out ten downvotes to whoever one pleased). Again, if it can attract enough users, it will then have enough clout to effectively control the narrative not just in its own communities, but throughout the fediverse.

And those potentialities, in combination with the fact that Piefed has gone from being rarely if ever even mentioned at all to, in just the last few days, being mentioned hundreds if not thousands of times a day in threads on virtually any topic, makes me highly suspicious.