In '82, Gretzky scored 92 goals on 24.9% shooting, however, he also lead the league with 120 assists. Does anyone think he couldn't have scored 100+ goals that season if he'd focused more of his energy into shooting the puck rather than passing it?
In '89, Lemieux scored 85 goals on 27.2% shooting, however, he also lead the league with 114 assists. Does anyone think he couldn't have scored 100+ goals if he'd wanted to?
Last season saw McDavid score 64 goals on 352 shots (18.2%), while leading the league with 89 assists. Does anyone think he couldn't have netted another 5, 10, or even 15 more goals if he'd played more selfishly?
It's certainly reasonable to think that Gretzky and Lemieux may have scored more goals, but when you break down what you're actually ascribing to them, asking them to score 100 is kinda an insult to their hockey IQs. Lemieux's case is a bit easier to refute than Gretzky's though, even though you're only talking about a 7 goal gap between 92 and 85.
You score goals by taking shots, and each shot has a percentage of the time it gets saved vs it goes in. In the case of Lemieux, his 85 goals were on 313 shots, a 27.2% shooting percentage. For him to score 100 goals, we obviously need to increase his shot totals, whether he maintains his seasonal shooting percentage or not. If we hold his shooting percentage constant, he needs to take an extra 54 shots (0.7 per game). If we add an extra shot per game (76 more), Lemieux only has to score about 20% of them to reach 100 goals. Thus, we turn the theoretical statement 'if Lemieux focused more energy on scoring goals, he would have scored more', into the practical statement 'because of his unselfishness, Lemieux passed up on average 1 20% shooting opportunity per game, or he would have scored 100 goals in 88-89'.
You can even look at Lemieux's previous season to see the folly of acting like shooting percentage is something under a player's control, especially when you start talking about higher shot volumes. Lemieux took almost all 76 of those shots the previous year, and none of them went in. He had 80 power play points the previous year, and 79 the next year, divided 22/58 and 31/48. Most likely, 9 shots that the goalie saved in 87-88 that were subsequently tucked in on the rebound (giving Lemieux an assist and a shot), instead went in directly (giving Lemieux a goal and a shot). The thought process and shot creation was exactly the same, the result was down to randomness and puck locations.
[The Gretzky math works out for him a bit better, as he only needs between 30 and 40 shots more to get those extra 8 goals.]
The math really is unforgiving. If you want to score 100 goals in an 80 game season, it requires you shoot 20% on 500 shots (6.25 per game), or 25% on 400 shots (5 per game). No single season of 5 or more shots per game has ever broken 20% shooting - the closest being Hull's 90-91 season where he was 1 shot away from averaging 5 per game (389 shots/78 games, 390 shots is 5, he shot 22.1%). Gretzky's 92 goal season was 4.625 shots per game at 24.9%. Other than that, the closest seasons were Mogilny in 92-93 (4.675 shots, 21.1%), and Lemieux in 95-96 (4.829 shots, 20.4%). The highest shooting percentages for a player averaging more than 5 shots per game are Esposito in 73-74 at 17.3% and Hull in 91-92 at 17.2%. [Until Chris Kreider did it 2 years ago, not a single player since the lockout had broken 20% while averaging more than 3 shots per game - though both Stamkos in 11-12 and Draisaitl in 21-22 shot 19.8% (Stamkos 3.7 per game, Draisaitl 3.4).]
[[Also, your Aaron/Ovechkin analogy is flawed because plate appearances are guaranteed, shots are not. Barring replacement, if Aaron played in a game, he would have 4 or 5 (or more) plate appearances. Removing 2000 plate appearances from him is akin to removing 473 games played from his 3298. Removing 2000 shots from Ovechkin would not necessitate removing goals - to retain 822 goals scored, Ovechkin would simply have to shoot 18.8% on 3.23 per game as opposed to the 12.9% he has shot on 4.72 per game. Especially given that in the last 7 years, Ovechkin has shaved off just over .25 shots per game over his 7 year average from 10-11 through 16-17 (4.53 to 4.25), while raising his shooting percentage from 12.1% to 14.6%.]]