Yeah, if you don't care about your domain name, it's less risky. Your readers may or may not want to open an email with a random domain, but if that's not a concern to you, go for it!
> I get the feeling this "UUUhhh! Black magic! Don't DIY with mails!" is fueled by marketing consultants who want to sell their services.
I think that's true, but in fact it's quite a bit worse than that... the email deliverability issues exist essentially because email has become a cartel of big providers who can collude on anti-spam schemes that make it very difficult for small players to break through successfully. They come up with both standards-based domain configurations (which in and of themselves are hard enough to get right) and out-of-band reputational databases that they are largely opaque, yet frequently shared, and with very limited & slow appeals. And depending on the recipients, if too many customers are on the same hosts, that intermediary host may throttle or block you if you send too many emails to them at once, regardless of the content. If you're a small fry ISP or random VM on the internet, you're totally at the mercy of these big players with no real recourse. They just don't care if their spam filters screw up. (And I dunno, maybe there's a pro-user side of this in that probably many people would rather their inboxes stay cleaner, risking the occasional false positive?
> I don't see why Google should care for technicalities. They can see the behavior of their users. The behavior should tell them that the mails are not spam.
It's not just Google (and even then not just personal Gmail), like depending on the makeup of your customer list, it could also include Google Workspace (business accounts that can set their own spam rules), Microsoft, Yahoo, Zoho, etc., and then tens of thousands of ISPs who make their own rules.
There's a lot of "it would be nice if" in email, but it's an arms race that got this way after decades of uncontrolled spam. I have no vested interest in any email service, but I often had to fix deliverability problems for small to medium businesses who mistakenly thought email newsletters should be simple... but they aren't today, because of the deliverability cartel. After doing that a few times and spending many days & weeks fighting these systems, I swore to myself I'd never make that mistake again. The micro-cents per email just weren't worth losing my sanity over.