I'm far from an authority but I do dabble in analytics and have for many years. So I'll speak from that viewpoint, just from my own experience as an analytic hobbyist
When making NHLe's for predictive purposes, there is not an agreement on one right way. From the work I've done with them, the single most predictive metric for forecasting offensive forwards is NON POWER PLAY GOALS PER 60. Gabriel Desjardin originally put forth NON POWER PLAY GOALS PER GAME, which is good too, but if you can break it to per 60 minutes it's even more accurate. I like to pull out the empty netters as well.
The fact is goals are goals. There is a variety of ways to score them and while they are often individually a product of luck, over time they become predictive with players who consistently produce and who consistently improve. As long as games are won and lost by the team who has the most goals, then players who can produce goals will be in big demand. Since past results are the best predictor of future results, players who's body of work includes consistent high end production of goals over time are valuable assets and identifying those players is a high priority on any team.
Assists have more variables. Often times 2nd assists are total phantoms. especially in junior games where teams assist totals at home are typically higher than on the road and some barns are more notoriously for gifting phantoms than others. Then there are the meaningless touches that get awarded as assists. A center loses a draw, but it's retrieved and sent back to the point where the d-man shoots and scores. Centerman gets second assist and he may have never touched the puck. Other assists aren't even meant to be assists. A harmless chip off the glass finds a friendly stick in the neutral zone who dangles a defender, nascars the net and finds a high guy in the slot, but the chip off the glass gets an assist.
There's been phantom goals as well, but few and far between. Even the back door tap ins seem like gifts, but the goal scorer still has to read the play, get to the right spot, maybe shake a defender, have his stick on the ice and be ready for the pass. There's skills there and intent that a lost faceoff or chip off the glass for example, just don't have.
Forwards who score goals translate their entire point totals, not just the goals. Many forwards who are goal heavy have closer to a 1:1 goal assist ratio. Elite players have the heavy goal totals and still maintain a 1:2 goals to assist ratio. Like McDavid, Tavares, Kane etc.
And the numbers bear out the theory. Forwards who don't score goals at the high end, but who's points are lopsided in assists rarely translate to the NHL game. When you see forwards with assist ratios of 3:1, 4:1, 5:1, 6:1 for example. That's all fluff. It rarely translates to the pro game. You look at the best playmakers in the history of the game - guys like Adam Oates and Wayne Gretzky. Oates assist to goal ratio was 2:1 as an amatuer and Gretzky was even less than that (roughly 1.6:1). They were great playmakers, but at the amateur level they also scored goals with the best of them.
Matt Barzal in his draft year had 12 goals and was almost 4:1 assist to goal ratio, and he's more than 8:1 this season. For his career he's over 3:1 with 55 goals and 163 assists and only 38 of those goals came at even strength - and this is a kid who plays near 30 minutes a game. Think about that - 38 goals in 174 games and people complain that we passed on him. People like to compare him to Nugent-Hopkins, but RNH could score. He had slightly over a 2:1 ratio with 57 goals and 120 assists, so he's right there on the edge of 2:1. And RNH scored those 57 goals all before he turned 18, where Barzal had 26 during the same time frame, and only 19 of those were non-power play. So I don't believe that his game will translate. It might translate to an international amateur tournament on the big ice, but I don't believe he will be wheeling and dealing on an NHL ice surface against NHL players like he does against 18 year olds in Seattle. He might I guess, but I don't think he will based on both my own viewings of him (over 100 games since bantam) and the analytic work that I've been doing for the past 6 years.
You never want to say a kid can't do something. It could be Barzal is a unique one-of-a-kind trailblazer that will make his own path and be the first WHL forward ever to carry an assist to goal ratio of greater than 2:1 to the NHL and have it translate. The only other guy I who had notably more than a 2:1 assist to goal ratio and played in the NHL from the WHL was Andrew Schneider, who had 108 goals and 258 assists. He played 10 pointless games in the NHL with Ottawa before heading overseas. He played in the World Juniors though. He did have an international game they figured. Anyways, I hope Barzal does it. He'll be a first and that would be exciting, but I don't think it will happen based on above.
That's what's special about McDavid. Like Oates and Gretzky, Crosby and Tavares, he does have that healthy assist ratio (1.5-2 range) but his goal scoring is also elite. Whereas Laine has the goals but he doesn't have the playmaking in his pocket like those guys did (the assists).
Laine vs McDavid is quite similar to Ovechkin vs Crosby. Laine and Ovechkin are better goal scorers (and could be predicted as such), but McDavid and Crosby are balanced elite players and better point producers (which also could easily be predicted as such).
Zac Senyshyn is a goal scorer. He's not Ovechkin or Laine but he's in that mold of high goals and low assists. He's not projected at their elite level but he could certainly turn out to be a high end producer. Certainly one of the best availabl this century at the draft position we got him at.