I like him, even bought his first Flask book. I just don't agree with him on this one. He (I hope is he, correct me OP) tries to make the short term scaling issues of one Fediverse project (Mastodon) the reason of why decentralization is bad or not feasible.

Author here: just to clarify I did not write a book on Flask, I did create the framework though.

Oh crap, my bad, I thought Miguel did, thanks for Flask anyway.