you are so fast to judge and say that an OS or an App is outdated as hell
In the case of FileZilla, we know. "3.42.1 (2019-05-08)" Almost . four . f*ckin' . years. For a networked application exposed to the internet, that's ancient. While you might get away with that version, don't call it safe, and don't recommend it to others.
The whole ordeal doesn't have to do with attitude, it's hard facts. If Apple has abandoned an OS, you're not getting fixes. Nada. Everything can happen.
Personally, I also run OS being outdated, but I have the knowledge to do that (and to secure it to maximum extent possible). You might have that knowledge, too, but many others definitely have not. Recommending outdated software to them asks for trouble. And, what do you think: Where will these users go complaining if that old version malfunctions or they get hacked? Here, as they expect support for the version they run. Which they won't get, as we can't support every version back to the start of time. User ends up SOL.
There are so many situations that would demand that someone need to install an old release, that is almost unbelievable that I have to explain these situations
While that might be, you are on your own with these. And, please do not connect them to any kind of net, at least not directly. Doing so asks for trouble.
It’s almost surreal to see this kind of arrogant behavior when interacting to a “contributor” that allegedly works with open source software. So maybe should I say to you: Shitty way of thinking?
It's easy to say "arrogant" if you don't like the facts. Doesn't change said facts, however. Again: I do run outdated OS and software, too (back to DOS 6.22 and Windows 3.11) but they are heavily locked down. And i would never advise others to to the same. Sure, it suck if the favored piece of software doesn't run anymore on the OS of choice, but it is how it is. I have a few restrictions on my current OS, too (Windows 7 fully updated), but I can't complain - it's my choice and my responsibility. And if something happens, it's MY fault.
The same applies to your situation. You alone are responsible for securing your environment. Please, please don't ever recommend the same environment to others, they might not have the knowledge to handle it.
When you say that you can’t talk about compatibility to old OS because you don't offer support to old software, maybe you should understand that the disclaimer about not offering support is the only thing necessary to add to an information about compatibility to old OS. Something like: “use this at your own risk, because this version is unsupported”, something so simple to do…
I'm bound to the rules of this forum and the project. No support for outdated versions, that includes offering them in the first place (the place you found is already for advanced users and thus not publicly announced).
"Use this at you own risk" sounds like an easy way out, at first, but, many users cannot properly assess the risks involved. That's why you don't see old version offered, disclaimers are getting ignored all the time.
As a technical forum, nobody should be forbidden to talk about any versions or any technical issues. If you as admin, is forbidden to do so, so I say it again: the answer to update an OS, when there is a compatibility solution, is a narrow-minded way of solving the issue. Better stay quiet.
You can normally talk about old versions as much as you like. What you are NOT allowed to do here is offering these old versions to unsuspecting others as a "solution". Which it is clearly not, just a risky workaround. Thus the "Sh*tty advice" hits the proverbial nail on the head. And no, we can't and won't stay quiet when you do things you shouldn't.
While I won't remove your link for now, I'm pretty sure the admin will.