Administration may prefer separate compilation machine and this of course adds costs and efforts. Dynamically linked binaries must not be allowed. Attacker can still use Perl and other tools that are installed to the protected system. This method has many weaknesses because it is based on obscurity rather than proper security. It can't be widely used because it depends on obscurity.
Obscurity can only slow down the attacker.
This can be implemented very easily because kernel needs only trivial changes. Methods based on security through obscurity should be easily implemented because there should be many of them and they must be thought again if some key persons leave the organization. After all this should result more effort for attacker than administration if automated. This method will stop most novice crackers that are using widely available root-kits as many of them cease working. To avoid weaknesses Comparison with unmodified binaries was a great problem so it should be made as difficult as possible.