You mean that the list wasn't great because it had players from the 80s in it? Laine has been a big kid for a long time now. The theory itself doesn't hold much value in regards to Laine. His development is/was stalled mainly due to an injury instead of having a late growth spurt. The point was brought up nevertheless and seems to be valid, nevermind if you like it or not. I would still like to hear why you disagree with the general notion with your own words instead of just "because someone else pointed out it wasn't great".
So since you think the data doesn't apply to modern day, lets look at some of the more recent u19 top scorers in the NHL who are eligible:
Patrick Kane 5"11
Jeff Skinner 5"11
Ryan Nugent-Hopkins 6"0
Nathan Mackinnon 6"0
Taylor Hall 6"0 (could be 6"1?)
Those are a few that came to mind but I could have missed a few. Feel free to add if so. None of these guys are over 6"1, so it looks like the theory holds time scrutiny.
"It just happens the best scoring players tend to be shorter"? Ok, lets look at the scoring charts from last season: Kane, Benn 6"2, Crosby, Thorton 6"4, Karlsson, Pavelski, Wheeler 6"5, Gaudreau, Kuznetsov, Burns 6"5 (D), Kopitar 6"3, Tarasenko, Seguin, Ovechkin 6"2. Now we have 6 players in top 15. Now when we look at the top scorers there suddenly is 6 guys who are taller than the average 6"1. This again enforces the theory as most of these guys probably wouldn't have been ready to play in the NHL on desired level at age 18 with possible exceptions of obviously Thorton (who played but wasn't exactly productive), Ovechkin and Kopitar, who were late birthday so wouldn't apply to the U19 rule. Also out of fresh memory, guys like Getzlaf, Perry, Scheifele, Benn (there's probably a lot more) - none of them were top picks. Why? All were one way or another late bloomers and would have been top picks in their respective draft years if they were easier to project, didn't have skating issues and whatever else I previously mentioned in my earlier post.
If you hadn't brought up the case of Thorton, I certainly would have. He's prime example of a guy who's got high expectations, doesn't get much anything done on the first season and then boom, a home run. Nash being another but less extreme example, you might expect a tad bit more from a fast 6"4 power forward who gets picked #1 than 39 points. A lot of the guys we both mentioned have similar development curve, which leads to the only possible conclusion, the bigger guys take longer to develop. Lindros and Lemieux (both generational talents) make prime exceptions to that rule.
The fact that there hasn't been #1 forward picks recently that were equal or taller than 6"2 is another good point. Looking back today, would you take Barkov over Mackinnon, Toews over Johnsson/Staal? <insert a forward taller than 6"1> over Yakupov? I think it would be a yes if you asked me in each one of those cases. Simply the lack of having big skilled and tall forwards being drafted first make an excellent enforcement to the argument. There are only a handful of players who were ready at that age, in a manner that they weren't considered risk picks for someone to go down first in the podium.
Everything here points out to what I said earlier and what ijuka originally stated, bigger forwards tend to be less ready due to physical elements I already listed (often having to re-adjust skating, stick-work, to body stress etc). This is derailing a bit but interesting to dig into. Also I have to say, this was a very good observation from ijuka, wouldn't even have occured to me without pointing it out.