Earlier quoted context omitted.
iterm2 puts config in ~/.config, while also having a directory in ~/Library/Application\ Support/ (habit). The author of iTerm has more credibility than the person you're replying to imho. If a program is putting text files a user is supposed to edit in that directory, that's a mistake. If the application doesn't live in ~/Applications and provide a GUI for editing configuration, the file belongs in ~/.config and the…
The XDG standard is a Linux standard, for compatibility between Linux distributions. Writing to ${XDG_CONFIG_HOME:-~/.config} on a non-Linux platform is like writing to ${APPDATA:-~/AppData/Roaming} on a non-Windows platform. I will never understand where the habit of assuming Linux standards are universal standards comes from. There is nothing in Apple's documentation about Application Support being incorrect for CL…
It's also objectively Wrong, the X stands for X Windows, what you are referring to as Linux is actually ABunchOfStuff/Linux, or as I've recently started calling it, ABunchOfStuff+Linux. macOS has an X server, still, to this day.
It's also pragmatically wrong, there are more than a dozen directories in my ~/.config directory. Be the old man yelling at the cloud all you want, or, maybe, follow the available standard like other sane, polite programs.
The nice thing about XDG? Just point XDG_CONFIG_HOME and XDG_DATA_HOME at Application\ Support if you want stuff to show up there. A program which doesn't check for those flags is not supporting the standard, file a bug.
So, to repeat myself: use XDG. That's what it's there for.