[olefoo]

"Because they are root and those are just files."

Just because you are root doesn't mean you should be able to do whatever you like to the filesystem at any time. Most modern unix variants (including linux) support file attributes such as immutability, see the man page for chattr(1) if you want more. In BSD land there is additionally the concept of Secure Levels which limit the ability of root to change file attributes under different circumstances; generally you have to reboot into single user mode to overwrite files or directories marked as immutable or delete ones marked as append_only.

[fhars]

According to the FreeBSD chflags(1) manpage:

  The chflags command first appeared in 4.4BSD.

Which puts it about seven years after this story.

[martinp]

"4.4BSD" isn't the same as FreeBSD 4.4, but actually version 4.4 of the original BSD which was released in June 1994.

[fhars]

OK, eight years, then. The timeline I found gave 1993 for 4.4BSD.