I know
@jigglysquishy already replied, but to give some additional comments -
Hockey-reference.com systematically underrates players from certain eras (particularly the Original Six era and the 1980's - which is why the results for Howe, Hull, Richard, Bossy and Gretzky are unreasonably low).
According to HR.com, from 1946 (the end of WWII) to 1967 (the last year before expansion), a span of 22 seasons, there were only two seasons that adjust to 60+ goals. That covers the peaks of some of the greatest goal-scorers in NHL history (Hull, Howe and Richard - among others). During the Dead Puck Era (1998 to 2004), HR.com says there were five adjusted 60+ goal seasons. This was an era that was relatively weak in high-end talent. When the players with the 2nd most, 3rd most, and T-5th most goals aren't in the Hall of Fame, you know that it isn't an era loaded with talent.
HR.com's output is telling us that the Dead Puck Era produced almost 8 times as many sixty goal seasons as the Original Six era did (on a per season basis). That conclusion is plainly false. The talent pool was larger during the DPE, but not anywhere close to eight times.
HR.com is also very harsh towards players from the 1980's. According to their website, that entire decade produced just three adjusted 60 goal seasons. There was with an immense amount of talent in the league - Gretzky at his peak, Bossy, several strong seasons from Lemieux - plus Kurri, Yzerman, etc. Yet 1930 alone (not the decade - just that one season) apparently produced more 60+ goal seasons than all of the 1980's!
I know that the people at hockey-reference.com mean well, but the authors aren't hockey fans. They try to use methods that work for baseball, but they don't always make sense for hockey. (Point shares, for example, can be horrendously misleading). Their output is probably usable if you're trying to compare 2014 to 2024, but it's essentially meaningless if you're trying to go much farther back.
(For what it's worth - I get a very similar number for Ovechkin's best ten years. I have 571, HR.com has 585 - a 2.5% difference. Stamkos is bang on - I have 473, HR.com has 474. Lemieux is very close - I have him at 499, HR.com has 503. I have Brett Hull at 511, HR.com has him at 518. The results are pretty close for players who peaked during the early/mid 1990's, or after the 2005 lockout. It's the other eras that HR.com struggles with).