You don’t really need to use any command-line interface or commands if you are running beginner-friendly Linux distro (Linux Mint, Zorin OS, etc.). Well, maybe except when things go very bad, but that’s very rare if you use your system like average user.

Then you should stop doing that. Even if you are running modern Windows, there’s no DOS in it to be seen, even though command interpreter (cmd.exe) is very close to what was typically used in DOS (MS-DOS, PC-DOS, DR-DOS, etc.) - COMMAND.COM. You are probably aware that the built-in commands there are actually very similar or the same as in MS-DOS. That’s because Microsoft didn’t want to make them different, probably mostly for compatibility reasons. There’s of course also PowerShell and Bash (and other Linux shells) if you run WSL (Windows Subsystem for Linux).

And these command interpreters are always (on NT Windows at least) opened in a terminal application, typically the older Console Host or the newer Windows Terminal.

What are you talking about? There’s no DOS in Linux, and I am not sure what the hell would that even mean.

Developers can just make a flatpak, publish it on flathub (or their own repo if they want, but ugh) and that’s it. Then you install the app through GUI package manager or by executing flatpak install <package name> command in your favorite terminal.

If you don’t count professional software, nowadays it’s actually the opposite. Very often in proprietary software there are features removed with no alternative provided by developers, or there’s one but actually it has nothing to do with what you actually want.