Not really.
MacKinnon didn't hit 70 points the first four seasons of his career. Crosby and Malkin have never come close to missing out on 70 points in a full season. Like, really really not even close. Malkin is averaging 97 per 82 and Crosby is averaging 105 per 82. MacKinnon's career high is 99. Now, you could argue that MacKinnon was pacing for 113 this year, but in Crosby's best year he was pacing for 132 in a league that literally had half the scoring. And you know who else paced for over 110 points this year? Evgeni Malkin. You don't even hear about that because MacKinnon taking the league by storm is just another Wednesday for Malkin. There's no comparison.
MacKinnon was probably better than McDavid this year, I'll give you that, but McDavid was the second most hyped pick of all-time. And he has a Hart, two Ross trophies, and two Pearsons, to MacKinnon's Byng and Calder. And even in the season of MacKinnon's life and an underwhelming season by McDavid's standards, McDavid still outproduced him (same story as Malkin above). Again, no comparison. Not yet.
Ovechkin is the greatest goal-scorer of all-time. Moving on.
Dahlin, we'll have to wait and see. I'm a believer in him. He just had 40 points in 59 games as a 19-year-old. He's basically Hughes and Makar except younger and nobody talks about him for some reason. Probably because of Buffalo. The kind of production Dahlin just had at age 19 on defense is the kind of production MacKinnon had at age 21 at center. If anything, I would take Dahlin out before I put MacKinnon in, because MacKinnon honestly can't sniff those other four.