Why can't I make a print-ready PDF from my artboards?

When I Export Artboards to PDF, there are no controls for print quality. When I save as, I lose my artboards. Is there a way to make PDF/X-1a pdfs from an artboard workflow?

I don't want to I have to rebuild my file from scratch with a new psd for each size.

*I understand that artboards function as windows into a single background, but there's no reason I shouldn't be able to export them as pages in a prepress pdf.