Quick reminder that ShellCheck is licensed under the strict GNU GPL 3.0 license. For many professionals your employer will often block / avoid GPL code, tools, and libraries.
Most companies that are anti-GPL aren’t so open about it.
Just because you can do something, doesn't necessarily mean you should. That rule applies to the implementation of corporate policies regarding licensing, too.
Indeed, which is why Linux is never found in a professional setting. /s
2) Not everything in the FOSS world is GPL'd.
3) There are plenty of users who have this restriction in their work and it is a real restriction to be aware of when discussing tooling.
4) That's just how the code is licensed and is related to the topic at hand.