No, PGP's weakness is that the Web of Trust is an unworkable solution for the general population for key exchange. It works fine for a you and your circle of crypto nerds, but as a general solution it's impossible.
IMHO this is a case where perfect was the enemy of good. Many possible solutions were rejected because there was a possibility that someone could MITM your first contact, even though in the real world this is unlikely. The key registries were almost a solution but none of them ever gained enough traction to be a default solution and mail clients were strangely hesitant to incorporate them even when they did implement PGP.
PGP was always half of the solution. Sadly they never figured out the other half. Microsoft almost got it working with Exchange, but even then you usually it only works on a single domain at a time. You can't use encrypt an email to someone at a different company even if they are using Exchange.
