A PR firm is just a different path to the same destination, though most of them DO suck.
Believe it or not, there ARE PR firms out there that chase a similar strategy to 37s. The 37s guys are awesome at PR. If you are not awesome at PR, then you can hire a firm. But yeah, if you hire a crappy firm that sends out press releases, you probably HAVEN'T been paying attention (and neither has the PR firm).