If a company allows his employees to use encryption, especially PGP encryption, it will run into trouble. Because AES128 is unbreakable, that means traffic which is routed in the intranet can't be monitored and checked for critical information. The idea behind Data loss prevention is, that a company has control over the data, and PGP bypass this control.
In Windows environments the problem is solved in reality by PGP Endpoint data loss prevention systems. That is computersoftware, who can read a message before it is encrypted. So the IT-department gets control back over his data. Such tools were sold commercially in a Security suite. But how is the situation under Linux? If the company has employees, who are using their own Linux distribution and PGP too, what is here the right choice in Data loss prevention? Could this be one of the reason, why PGP is not very often used?