Comments like this are inevitable and represent Facebook's attempts to induce us to route all of our communications though its platform. For the quoted commenter, it's probably too late.
PGP fills a niche that OTR and Axolotl do not. It provides a bunch of operations that are not supported by OTR (anything that requires signatures that are verifiable by third parties). PGP is used by the masses (package signatures and similar functions), it's just that they don't use PGP for communication.
Comments like this are inevitable and represent Facebook's attempts to induce us to route all of our communications though its platform. For the quoted commenter, it's probably too late.