Previously Gatekeeper had the option to to run apps from "Anywhere", that option has now been removed from GateKeeper settings
The option to run unsigned apps (i.e. apps from "Anywhere") still exists, but rather than being a global setting, it's now handled on a one-off basis by bringing up the contextual menu on any unsigned app and telling it to Open. I think it provides a warning about the risks and then confirms that you want to still open it, but after that it'll run just like any other app, no more warnings or anything. In the last year or two, I've only encountered one unsigned app that required I go through that process, and I'd consider myself a fairly advanced user (as I imagine most other people here would).
Avoiding the MAS is becoming more difficult for Mac users.
In practice, I don't think this is actually the case. Again, I've only encountered one unsigned app in the last year or two. Were that not the case, I might agree, but the vast majority of Mac developers seem to have a certificate at this point, and the second option you listed is the default one, so their apps run with default settings, which means that no one is really being pushed to the MAS. And stories like the ones being described in the summary are becoming increasingly common. Indications seem to point towards MAS usage being in decline for the last few years among advanced users, and novice users are dwindling too as their attention is increasingly drawn towards mobile platforms.
I do agree that macOS is converging on iOS, but I think we're still a good few years away from it becoming that locked down.