If gmail decided to ban a number of accounts due to something like a DMCA claim, I would be unaffected by that.
The same is not true on GitHub which is one Website. Every fork of this project on GitHub was affected by this claim...
They did let one-in-20 or so emails through, but everything else got to gmail recipients’ Spam folder. I wasn’t able to troubleshoot this with Google tools, and there’s no one to talk to at google.
(Worst thing, you get no feedback - except realizing a month later that someone didn’t get an email you sent)
I gave up and replaced small ISP with fastmail.
My bottom line is that, no you can’t really run your own SMTP server anymore unless google, Microsoft and fastmail let you, by virtue of hoisting 90% of your recipients.
I have many domains that I use to send and receive mails, and I have personally never had these issues.
Now if I did have a gmail account, I suppose I would have to check the spam folder regularly. But I don't have that problem with my server, it affects their users more so than me.
in a federated world, while github may still host all the code, you could potentially submit prs with and have metadata about a repository, such as issues, spread across multiple different providers. Instead of needing a github account to contribute, you just need an account that github could federate with.
This would mean that if Github did start doing something you didn't like, you would be able to change code host without losing the metadata.
Potentially, anyway.
Federation doesn't prevent centralisation if the service is good enough; it just makes it less painful to decentralise if better competition exists. It also diversifies ownership of data, which is in general a good thing for consumers - and a bad thing for big tech companies that wish to make money off of analytics, which is why we will never see current social media platforms allow federation with other social networks, even if would be better for the world and consumers.
Gmail has an enormous market share (about 40%) but I don't think that's related to the nature of SMTP, more about their incredibly competitive free tier and the decidedly not federated groupware for their business offering.