That is incorrect. PP TOI and raw PP production actually have an insanely high correlation.
Somebody should really tell Alex Ovechkin, who led all forwards in PP TOI and was 68th in PP production last season.
Or Nathan Mackinnon, who played 9 more minutes on the PP than Leon Draisaitl and scored 13 points fewer than him.
Never mind the fact that Patrick Hornquvist, he of 88th highest TOI among forwards last season, had the league leading ixG at 5v4, understandable so, given his position in front of the net on the PP as compared to the litany of talent around him with more TOI but nowhere near as dangerous a position.
And that ignores the obvious idiocy of suggesting that because a Dman plays more minutes than a forward, he should be expected to have more points than the guy running the PP off the half-wall, or receiving the one-timer pass.
TOI obviously matters. More time is more opportunity for goals to be scored. It's obscene to suggest that a player given equal time in every role would score or collect points at the same rate in every role. Its obscene to suggest that any player would score or collect points at the same rate in every role, in any system.
Role and system are huge influences as STs are the area of hockey most directly impacted by coaching systems. It's much more rigid and much lest fluid than 5v5. This is one of many reasons why 5v5 production is so much more important in evaluating a player than PP production.