I've done some subcontracting for engineering firms and most of the "engineers" I worked with did not have PE certification. There were a few senior guys with PEs who signed off everything. I don't know, but after seeing the reams of drawings/plans I find it hard to believe that this system of requiring only PEs to sign off on projects is actually achieving the risk mitigation that is claimed because I don't think the volume of work is realistically reviewable by one guy.
I'm more inclined that PE certification, like so many professional certifications, is mostly about eliminating competition and running a kind of cartel, especially when it gets the kind of self-policing powers that most legislatures grant professional certification boards. If you can obtain a legislative monopoly on your trade *and* gain the power to determine and police who can enter your trade, you're doing pretty well.
I would argue that by making PE certification so complex, thus reducing the number of PEs, engineering is worse off because fewer PEs sign off on the work of non-PEs without truly applying whatever their special magic is to the work (simply too much to check).
It would make sense to make PE certification somewhat easier to obtain without essentially compromising the knowledge required to gain it. You would have a larger pool of people shown competent at engineering, but this would create problems for the engineering business which would face more competition.