there is definitely an argument that, to a point, the smaller hockey talent pool means a less talented player can make good if better nurtured.
This hits the nail right on the head.
The NHL puts a lot of effort into selling the idea that we are seeing the most talented group of players ever produced. I find that claim dubious for a number of reasons (spelled out at length in other threads) but very specifically, I don't think the data supports claims that the hockey development system is actually bringing the most talented players to the forefront. What we see
far far more often is that talented players
with excessive levels of training access and financial means are able to continue moving up the ladder while other equally-talented but less-privileged prospects hit various barriers along the way.
Another data point:
Brothers in the Hall of Fame
MLB
Harry and George Wright (1870s)
Lloyd and Paul Waner (1920s-1940s)
NBA
Paul and Marc Gasol, presumptive (2000s-2010s)
NFL
NONE
NHL
Lester and Frank Patrick (1900s-1920s)
Buck and Frank Boucher (1910s-1930s)
Bill and Bun Cook (1920s-1930s)
Charlie, Lionel, and Roy Conacher (1920s-1940s)
Doug and Max Bentley (1940s-1950s)
Henri and Maurice Richard (1940s-1970s)
Tony and Phil Esposito (1960s-1980s)
Daniel and Henrik Sedin, presumptive (2000s-2010s)
We can see the effect of rapid expansion from the 1960s through the 2000s -- brothers now are much more likely to "only" make the NHL or "only" be All Stars rather than full-on Hall of Famers together -- which provides some proof of concept that the proxy is giving a reliable reading. I would expect an analysis would show similar impact on stats, all-star awards, etc produced by brothers during the same time frame.
The persistence of this effect across eras seems to indicate the obvious, that hockey simply draws from a narrower population base than other sports. But there are orders of magnitude involved which seem to outpace the population difference. There are few equivalents to the Patricks, Conachers, Stastnys, Sutters, Staals, etc in other sports whereas it's a regular feature in the hockey world, generation after generation. That rather strongly seems to suggest that there are anti-competitive forces at play, selecting for opportunities according to factors other than athletic talent and dedication.