Name one software that has ever been feature complete. Software only reaches EOL.
Discussion
cat
Cat is bash command.
No it's not. It's a compiled command part of GNU. You can execute it with a bash command, but it is a normal piece of software that has been feature complete for what, 50 years or more, thereby giving you an example.
I'm surprised that a software engineer of your caliber didn't understand what 'cat' was.