Not the only slogan actually, "The Dot In Dot Com" ran with several important campaigns at the beginning of the nineties and was a crucial security public service announcement that's explained here :
The trailing dot then means the name is to be used actually exactly only like that, it is specified in full, while the name without a trailing dot can be tried with a domain name appended to it. Or even a list of domain names, until one resolves. This makes people want to use a trailing dot at times, to avoid that domain test."
Back in the nineties I stumbled over the dot, when a friend of mine claimed his mail address was `something@aol.com.` insisting on the dot. I proved him wrong, claiming it didn't matter. Only a few years later, when dealing with DNS config I learned the truth... now it's knowledge I can use to be alone in a bar.
But more recently that knowledge got some relevance in Kubernetes clusters to me: By default they use the `cluster.local.` domain. As that is configurable, now many people leave that out and rely on the search domain config. In consequence in some situations a broken service may try to connect to the outside and with bad choice of i.e. namespace names might leak as valid host names on the public DNS ... which in worst names can lead to a connection attempt from cluster to some foreign system.
You've hit the nail on the head, that's a perfect analysis, and it wasn't an isolated incident!
But they'd been like that for a long time, since before I started there in 1990, long before Java. They DEFINED themselves in terms of Microsoft, to the extreme extent that when Sun Microsystems fell apart into separate divisions, they actually named one of them "SunSoft" to directly position it against Microsoft. As if.
The management at Sun didn't consider Java to be a programming language or software platform, they considered it to be first and foremost their primary weapon of mass destruction in their apocalyptic war against Microsoft, and they didn't consider Java developers to be loyal cherished customers, they considered them to be disposable brainwashed mercenaries in their World Wide War against Microsoft.
It was funny when Sun proudly and unilaterally proclaimed that Sun put the "dot" into "dot com", leaving it wide open for Microsoft to slyly counter that oh yeah, well Microsoft put the "COM" into "dot com" -- i.e. ActiveX, IE, MSJVM, IIS, OLE, Visual Basic, Excel, Word, etc!
And then IBM mocked "When they put the dot into dot-com, they forgot how they were going to connect the dots," after sassily rolling out Eclipse just to cast a dark shadow on Java. Badoom psssh!
Sun totally dropped the ball fighting their true original enemy AT&T, and they should have put all that effort and energy into improving SunOS and railing against AT&T after SunOS finally beat System V in the Unix market, instead of capitulating to AT&T AFTER SunOS won the Unix war against System V, and then rolling over, giving up, selling out to their mortal enemy, and becoming Solaris.
To port my favorite cross platform Apple/IBM joke:
https://daniel.haxx.se/blog/2022/05/12/a-tale-of-a-trailing-...
THE money quote :
The trailing dot then means the name is to be used actually exactly only like that, it is specified in full, while the name without a trailing dot can be tried with a domain name appended to it. Or even a list of domain names, until one resolves. This makes people want to use a trailing dot at times, to avoid that domain test."