Most of the complaints about it...
... are because those sysadmin need to learn something new and they really hate it, and fear it.
They like a fossilized Unix that must not change since it was written on stones in 1970. They're happy with it because they are frightened anything new will make them obsolete like Unix is, unless they update their skills.
It's far too comfortable to keep on using the same commands and scripts over and over.... and keep everything stuck in 1970. My Linux sysadmin is a perfect example of them....