Another factor could be that hockey fandom is just the right size for the "sort the whole tag by kudos and read everything on the first few pages" approach, which, once the fandom's been established for a while, tends to lead to <100 fics having very high kudos (because people read through the top of the tag and leave their kudos on top of whatever kudos the fic had originally), and the rest of the fanworks stay at the fandom baseline for kudos numbers without that boost from newbies binge-reading. Add that on to the fact that a few of the juggernaut pairings are slowing down and you might have a fair hypothesis.

And more related to what you said: I did a little noodling around on the Wayback Machine to see if I could figure out how quickly things accumulated kudos, with disappointing results (the sample size was small and the results were inconclusive), but it generally looked like a lot of the stuff from 2015 hit 1k within 4-6 months of being posted. So it wouldn't surprise me if a post-Kane debacle work hit 1k eventually, but it doesn't seem to be happening as quickly as it did in at least parts of the recent past.