That's actually an important distinction. From reading the article I was under the impression that Germany was saying GDPR mail providers wouldn't be able to send to a recipient whose server wasn't configured to properly support TLS. While big providers are mostly TLS now and can reasonably be expected to fix the issue if lacking it became a missing message problem, and the smallest level of private/vanity mail servers are mostly outsourced to hosting companies than can do automated mass updates if needed (like they did for HTTPS recently). But in between those poles is a major problem area. Although individually small there's a huge swath of generally smallish mail servers that are nominally self administered but effectively unmaintained unless something appears broken to the user. Lots of them would have fallen through a crack because their owners don't read the tech press, and they do business with Europe infrequently enough that it wouldn't be an obvious problem.
By "that long ago" do you mean last week? They've gotten steadily skinnier with tinier type over the last decade, but I still have 2 or 3 pushers of them dropping them off at my doorstop.
I think the last time i used one was pre-smartphone when I needed the number for a pizza delivery shop during a power outage.