I don’t think you can separate systems, equipment, and talent level in a meaningful way. Systems matter more because there are very few truly bad skaters in the league now, skating talent has improved which means at the low end you have players who can execute the demands of the system more reliably and at the high end you need a good system to contain the McDavid/MacKinnons of the league. Composite sticks made new types of talent possible like Matthews/Bedard’s drag shot that changes angles and point of release several feet across in full speed using defenders as screens. The rise of snap shots in general opened up new skill sets and we have arguably a golden age of hand-eye coordination net front deflection plays that have killed the classic booming point shot. This forces systems to change, which opens up new niches of talent, which forces equipment adjustments, which forces systems to change, which forces..
I agree that it's difficult to separate.
One could argue that players have never been more skilled, simply because the skillset keeps expanding. And that this will likely continue going forward.
When it comes to talent though, it's a bit murky, because that talent is also between the pipes, and on the blueline.
Either goalies have suddenly become terrible despite all of the advancements in goalie instruction at increasingly younger ages, or there's something else at play here.
I think there are too many players in the league nowadays for "more offensive talent" or "less defensive talent" to be a major driver in what happens with goals per game.
It's more likely in my mind to see sweeping changes, like the crackdown on obstruction that led to the post-DPE era (more PPs initially, less hooking now, which is to the detriment of defensive play), the proliferation of composite sticks (which have no defensive advantage), or the shrinking of goalie equipment (which can only benefit scorers).
Meanwhile, the post-80s DPE came about with fewer and fewer enforcers playing regular shifts on the bottom lines, the emergence of better skating bottom-six players specializing in defence, more equal icetime distribution, the introduction of the trap across the league, the increasing size of goalie equipment, and the reliance on obstruction (see: can opener) as a legitimate defensive approach.
I see that some people like the big round numbers without context, and that's fine. I just prefer to interpret those numbers with a little more context.