@Shamar I have been seeing similar trends, but also counter-examples. Specifically I like to point to CUPS as an effective federated WebService. And The Fediverse too.
For federation to stick, there must be a reason beyond federation to embrace it.
I don't even know where to start.
Near the end I went back to the beginning to double check that it was not published on April 1 last years!
I think @bob summarized my opinion well: https://mastodon.social/web/statuses/101700686236282442
It basically attack a straw man: it setup a dumb metric for success (even distribution of 2019's users) and then argue that SMTP (!!!), XMPP, HTTP and ActivityPub (that the author do not even cite) failed because they didn't produced such metric.
Except nobody ever had such goal.
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