Instead of, for example in your last example simply labeling something you seem to not like as "laughably weak"- do you have any specific reasoning? Again, I'd like to emphasize that I don't advocate obscurity in place of other methods, but on top of additional methods.
Let's try some silly extreme examples of obscurity. Say I put up a server running OpenBSD (because it is less popular)- obviously a recent version with all security updates-, and it has only one open port- SSH, reconfigured to run on port 64234, and attempting to scan all other ports immediately and permanently drop the route to your IP. The machine does not respond to pings, and does other weird things like only being physically connected for 10 minutes a day at seemingly random times only known by the users, with a new IP address each time that is never reused. On top of that, the code and all commands of the entire OS has been secretly translated into a dead ancient language so that even with root it would take a long time to figure out how to work anything. It is a custom secret hacked fork of SSH only used in this one spot that cannot be externally identified as SSH at all, and exhibits no timing or other similar behaviors to identify the OS or implementation. How exactly are you going to remotely figure out that this is OpenBSD and SSH, so you can then start to look for a flaw to exploit?
If you take the alternate model, and just install a mainstream open source OS and stay on top of all security updates the best you can, all a potential hacker needs to do is quickly exploit a new update before you actually get it installed, or review the code to find a new one.
Is it easier to rob a high security vault in a commercial bank on a major public street, or a high security vault buried in the sand on a remote island, where only one person alive knows its location?