Steel and Comtois have scored at a higher pace in their careers than Rakell did through his first 95 games. But no, players are done developing at 50.
It's amazing to me how carefully, clearly and explicitly I can say "probably," and some person will *immediately* pretend that I said "certainly."
This is called survivorship bias. Rakell is notable because he was an exceptionally strong late bloomer. If you *all* the players who got off to a similar start to Rakell, the average result is much much worse. And even he's not *that* good of a player. He's a guy who seems great because we don't have anything better. He's never received a vote for a major award (besides the Byng), made exactly one All-Star game, never appeared on the points leaderboards. He's a second-line forward.
And you very carefully said "games" instead of "age" because you know that Rakell got a ton of games in at a very young age, so you get to shift the curve to make it seem like Terry and Steel are way younger than they are. The proper comparison is age, not games played. You'll notice that I listed both games and age in my hypothetical, but you only listed games because you have to distort what I said in order to get the result you want.
So Kase, Rakell, Silfverberg are mediocre players at best?
Age-22 PPG
Rakell: 0.60
Kase: 0.58
Silfverberg 0.39
Terry: 0.24
Rakell, as we described above, is good but nothing special. Silfverberg is a little above-average but not much. Kase is extremely average.
Terry is on career arc that leaves him well behind all of them. Right now, Terry's career arc is very mediocre. Maybe he'll shoot way up beyond that arc, maybe he'll come in way below it, but the *probable* course from here is mediocrity. If you take where he is now, and add on the amount the average player gets better between 22 and peak, you still get a pretty mediocre player.