When it comes down to top ten of all times, I believe all around play is important. Marleau has the most games ever, who in their right mind would place him amongst even top 100? Ovie has struggled to be a ppg player when Crosby hasn't. Ovie only has two finishes in the top five in the past ten years, and I think he has missed top ten seven times during that time. So of I'm not mistaken, he been outside the top ten scorers 8 out of 16 seasons.
In all his seasons but one (11/12), Ovechkin finished top20 in points. The distance between top10 and top20 finish is usually small, roughly 7 points if we talk about jumping from #20 to #10, and may be as small as 2 points (see Ovechkin's 17/18 as an example).
Outside of O6-era players, who played when there were only 18 first-line players in the whole league, only two players have more top20 finishes in points than Ovechkin: Gretzky (18) and Dionne (16). Tied with Ovechkin is Sakic (14), Jagr with his insane longevity has only 13 top20 finishes in points.
Now here is the difference between Ovechkin and Dionne/Sakic who enjoyed similar longevity in the points race: both Dionne and Sakic had only 4 seasons when they received more than 5% of Hart votes. Ovechkin has 9 such seasons, and of post-expansion players only Gretzky has more.
One example of why Ovechkin's seasons outside of top10 in points matter: look at 15/16, when Ovechkin won the Rocket in a commanding fashion (17 goals ahead of #10 in goals), but finished 15th in points: he got a higher fraction of Hart votes that season than Crosby did the season before (14/15). Crosby was above ppg and top3 in points; yet, the Hart voters were more impressed by Ovechkin in 15/16.
And btw, Ovechkin is currently 20th in points - for the 15th time in his career if he holds on to that for another 10 games.