I know many prepress professionals who'd emphatically disagree. In theory, you are absolutely correct. Much better to have a "finished" format than a program you have to 1) interpret and then 2) figure out how to fix.
But overwhelmingly, the PDFs print shops get are finished improperly, and Adobe has provided no tools, other than Acrobat, for fixing them. And when you finally do, what happens to that PDF when ripped? It turns back into PostScript. Adobe stepped away from the printing industry, and left a big hole that third parties are only now beginning to fill.
I suspect the average prepress technician spends more time working on PDFs then they ever did working on PostScript files.