Mario had 1 peak season that is on par with Gretzky's 5 best seasons. Maybe 2. But then the best 3 seasons after that are also Gretzky's. Put another way, if we ranked their combined 13 best seasons, 9 of them would be Gretzky's. It would be something like this:
1. Lemieux '89
2. Gretzky '82
3. Gretzky '84
4. Gretzky '85
5. Lemieux '96
6. Gretzky '86
7. Gretzky '83
8. Gretzky '87
9. Lemieux '88
10. Lemieux '93
11. Gretzky '91
12. Gretzky '89
13. Gretzky '81
Peak Mario is arguably equal to peak Gretzky in terms of per-game offensive output, and only for stints of 1 season at a time, but mostly less than that. Gretzky sustained those totals many more times. Sustaining peak totals in hockey is frigging hard! It's tremendously valuable to a team. And that's the huge gaping inescapable gap in your logic that utterly disconnects it from reality.
Emmitt Smith never touched the peak of Barry Sanders. Like, not even close, so that comparison is very bad. Smith's longevity vs Sanders's peak is a good argument because there is a trade off. The discrepancy in both metrics is large.
With Lemieux and Gretzky, there is no trade off. Peaks are, at best (for Lemieux) basically equal, while Gretzky achieved far superior results in the long run.
There is simply no rational basis to have Lemieux equal.
And herein lies your problem. You have Lemieux's 1993 season as TENTH on this list, and during that year he won the scoring title while missing 24 games with cancer! It's arguably the greatest season in NHL history, scoring 160 points in 60 games while missing a quarter of the year in the middle with radiation treatments. He chased down Pat LaFontaine after being down 25 points. He scored 2.66 points per game that season which is a 224 point pace, the highest points per-game mark for a season ever seen in NHL history. In the 90s! When goalies actually wore pads and started to butterfly.
And you have it TENTH! HAHA. In terms of difficulty it's got to be first on your list. This shows that you're just going down the list and counting up points.
Also, Lemieux's 1996 season was absurd at that time. Comparing the Smythe division in 1982 to the Northeast division 1996 in terms of ability to score is a little crazy, and all of Gretzky's top seasons are those blowout early 80s years. Even in Gretzky's monster year of 1985, Lemieux's 2nd year, Gretzky scored 52 goals and Lemieux 48 that year. The difference was an absurd 163 assists for Gretzky vs. "only" 90 something for Mario. Mario was playing on an absolute trash team that year while Gretzky played on the eventual cup champs. Do you not think Mario would have scored a massive amount more if he was on that 85 Oilers team? Gretzky basically never played with a bad team in any year of his peak except his very first year, and that team was no cellar dweller like the mid-80s Pens.
Anyone can look at pure numbers and say that number is greater than that number. There's so much more nuance that you're missing man.
And it's good that you admit peaks matter. Emmitt Smith has way more yards than Barry Sanders, way more touchdowns, also he's up 3-0 in championships. Really the only thing that Sanders has on Smith is the highlight reel (just like Mario), and the better single seasons (Just like Mario). I'd argue, just like I've been, that Mario has the top two seasons on your list, and three of the top 5. Wayne has more total top seasons. Just like I've said, Mario's peak is higher, Wayne's full career is better.