Why is ease of hosting a mail server rated so well ? How is “leveraging email hosting services” decentralized in any way ?

Because somebody there doesn’t even understand you’re supposed to host an email server as easily as hosting a web server with a website. While in reality you’ll learn all the Satanish obscene lexicon before making big email providers accept your mail.

I’m exaggerating probably, but ahem.

That said, in my humble careless incompetent “let’s-go-back-to-year-2005” opinion we need a new email standard, spiritually same, but qualitatively different, like the upgrade from prehistoric email with UUCP paths to something more modern, only this time cutting down all the DMARC and DKIM bullshit and simply using pubkeys in To: and From: headers, with the email itself signed by the author, by mail server and maybe by something else. One can make encryption of email content the baseline norm while we’re at it. One can even get rid of the attachment of identities to mail servers and use servers similar to how NOSTR has relays. I mean, what I described already is just NOSTR with nostalgic aesthetics. Maybe also similar to some kind of Fidonet reimagined.