1. I would agree, Nighbor is seldom described as a great goal scorer. But Messier was nothing special in that regard either. The greater scoring prowess of Joe Malone and Newsy Lalonde is possibly why history has remembered them more than Nighbor.
2. The assist question isn't really something that I give a great deal of concern to. I mean, we're talking about seasons where 10 assists might lead the league. They weren't even officially recorded by the NHL in 1917-18 (not entirely sure when they started appearing in players' records for that year, but sometime in the last 10 years I think). And you have the small league problem to the extreme. Just three teams in some years. So the schedule is highly imbalanced in a sense. At the end of the day, the stats from the first handful of years of the NHL are nice to have for sure, but I just don't give them the same gravitas as a bit later when the league got up to 6-10 teams.
The establishment itself doesn't seem to have considered them exceedingly important either. We had the Hart trophy introduced in 1924. The Vezina not long after, plus the season-ending all star teams. But no trophy was given for the leading scorer until the post-war era. As we can glean from the newspaper accounts as well, offensive and defensive roles seem to be less clearly defined among the best players. Simply put, both were important. Unlike the modern era where it is often said that a forward's job is to score, or a defenseman's job is to defend.
3. Does it matter? Everyone was playing under the same conditions and Nighbor seems to have been better at defending from the forward position than anyone else. There doesn't seem to have been anything stopping Joe Malone or Newsy Lalonde or Howie Morenz from adopting the same tactics and excelling, yet as best we can tell, they didn't.
As an aside to this...and somebody can correct me if I'm wrong...but the puck could be physically passed forward throughout all of history. The receiving player just had to be behind the passer when he released the puck. This is definitely different than if a pass was only allowed to physically travel backwards like a lateral in rugby or gridiron football.
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I think for me, the verbal praise directed at Nighbor from opponents, coaches, teammates, media, practically everyone, during and immediately after his career is where the meat of his case is. All the Stanley Cups, both East and West, and the considerable support in early Hart voting (when he was getting towards the end of his career) seem to back this up well enough to put to bed the idea that much of this praise was just fluff, hockey players generally praising everyone, etc.
There are examples throughout history where the stats sheet just betrays the reality of how effective a player was. I guess we can never be 100% certain that Nighbor is one of these cases, but the evidence is strong. The modern example is Mark Messier. Somebody doing research a century after the fact, with access only to the NHL Guide and Record Book, is probably going to conclude that he was a great player, but not necessarily better than say...Jari Kurri. I mean, did any of us think Nighbor was better than Cy Denneny until a decade of diligent research shone a light on a truly forgotten all-time great? When we did this project a decade ago, I think Nighbor was on the fringes of the top 100. And I mean, it's not like the era itself was just brushed aside. Lalonde and Taylor made it in the top 50 I think. Cy Denneny, Joe Malone, I'm sure they were on that list as well. I'm sort of rambling now, but it really is fascinating case study. A player now being considered for a place within the top 20 of ALL TIME was just forgotten about for like 60 years. Even Stan Fischler...who had guys like Frank Fredrickson and Duke Keats and Dick Irvin on his Top 100 list managed to completely overlook Nighbor.
