Sure -- I can only describe what they do differently, not so much why.

I also jumped the gun by suggesting polyphonic effects aren't pitch shifters -- I was thinking of the reasoning behind my own setup and not the broader possibilities. I should have said something like polyphonic vs. monophonic or octave vs. harmonizers. There are two typical reasons to place shifters early -- polyphony and octaves. People usually want to use octave to make their instrument sound like another instrument, not as a conspicuous effect. The Octave Multiplexer is analog and monophonic, but it still goes before dirt.

Now most effects are jumping on the polyphonic bandwagon, not just with octave stuff but also with harmonizers and arpeggiators. It may be that most things now (Whammy, Drop, Pitch Pirate) would be placed early in the chain -- just after the compressor, which will improve tracking.

When people talk about the POG's amazing tracking, it's usually in reference to what was once a unique ability to digest chords. It also had a more complex tone than its peers, that detuned shimmer. There was a time where pitch shifters would be expected to simply regurgitate a divided/multiplied frequency. Don't ask me what that means, but the point is that even if you tried two notes at once with a pitch shifter it might start to confuse them glitchily. It's also 'flattened', processing out instrumental timbre. The first polyphonic stuff doesn't exactly sound like your guitar either, but it hedged its bets by layering multiple reproduced voices based on your signal, like a vocoder (heck, maybe it is a kind of vocoder).

When I hear 'pitch shifter', I think of the Boss PS series, which also carry a delay function. These usually go where you're putting the Hotone, somewhere among the modulators. As harmonizers/detuners they can be used to a similar if more extreme effect.