So 2012 to 2016 had only "one or two high end scorers" which brought the league GPG from about 3.00 to 2.73. And now that there are more than "one or two high end scorers" starting in 2017, the league GPG has risen to about 3.14.
Let's assume that a "high end scorer" brings his team, what, 10 to 15 more goals vs. an average first liner. Guess how many more total goals do you think it takes to move the league GPG from 2.74 to 3.14.
About a thousand.
So by your theory, the four more "high end scorers" that have come into the league since 2017 have accounted for an average of 250 more goals scored.
Sort of, but you're way off on a few things.
League scoring has only been 3.0 or higher once since 1995-96, and that was mostly because in 2005-06, the league was handing out power plays like they were Halloween candy. 96-97, 2006-07 and 2008-09 were the only 3 other years over 2.9. Other than that, scoring was consistently pretty low (2.54 - 2.79 GPG) for almost 20 years.
Over that time, the range between the top and bottom players shrunk. Low end guys coming into the league got better, elite guys coming into the league got fewer and farther between, and averages stayed pretty much the same. By the time 2011-12 rolled around, all the previously elite guys had aged out of the league, leaving only really Crosby, Malkin and OV as the truly elite players in the NHL. Over the next 4 years, one of Malkin/Crosby was generally hurt, and OV was more about scoring goals than amassing 100+ points, so the race for the Ross was wide open for that next tier of guy to jump into the top 5, and we saw guys who were clearly not at that same level, like Benn and Getzlaf and Seguin either take home hardware or finish in the top 5. And Crosby beating Getzlaf, Giroux, and Seguin isn't the same level of accomplishment as Crosby beating Thornton, Lecavalier, and Heatley. He won both years, but one is much more impressive, right? So why do they both count the same? This is why I detest using raw trophy counts and scoring ranks as evidence of anything.
Starting in 2013, drafts started getting much better and by 2017, there were a handful of new elite guys at the top of the scoring charts, putting up 100+ point seasons. The next year, there were more. The year after that, even more. In addition to the elite guys, the non-elite guys these new elite guys played with are scoring more too. And a lot of the next tier of guys are now on 2nd lines instead of the top of the scoring charts, and scoring more than 2nd liners from before. The only way averages don't go up significantly in this scenario is if there's also a lot more guys who can't score for shit coming into the league, but that obviously didn't happen. And none of this happens without the plethora of elite talent from the post 2013 drafts at the top of the league today. That's what finally drove scoring up so much, without any question in my mind. And we keep adding more elite talent, so I'm not sure when scoring is going to come back down. Probably not until there's another long string of weak drafts, based on what I'm seeing.
If you want to claim it's some other reason, you're going to need some pretty strong evidence to convince me.