I think most people accept that sports change over time and it's difficult to compare historical players with current ones.
Ignoring rule changes, there's the fact that athletes can collect so much data about their performance and use that information to improve in ways that just weren't available 30-50 years ago. Not to mention all of the scientific breakthroughs society has achieved in our understanding of the human body, nutrition, pharmacology, etc. An athlete born in 2020 has a huge advantage over one born in 1920.
Look at clips of Wayne Gretzky from the 1980's, which is also when he set all-time records that have not yet been surpassed (and people still believe never will, though Ovechkin has a chance at the goals record)
What's incredible isn't what he's doing, it's what everyone else around him is NOT doing.
* He's skating fast but not that fast (compared to modern skaters)
* His shot is accurate but he's not a sniper. Many shots never leave the ice
* But the defenders have absolutely no checking ability
* And the goalies are upright! The butterfly style hasn't been popularized yet! They're just awkard sieve slowly shuffling around in net.
Ignoring rule changes, there's the fact that athletes can collect so much data about their performance and use that information to improve in ways that just weren't available 30-50 years ago. Not to mention all of the scientific breakthroughs society has achieved in our understanding of the human body, nutrition, pharmacology, etc. An athlete born in 2020 has a huge advantage over one born in 1920.