I do agree that the audience and grassroots nature puts Splatoon in a weird spot compared to other shooters or fighting games though. Especially with the perception the series has amongst the people most likely to enjoy it (people who already play shooters/competitive games)
It's definitely a multifacited issue, I just see recognizable teams being a big pain point. More comp youtubes, better balanced TC/RM/CB for variety, better marketing, better official support, etc. all could help too. It's also the one issue I feel I can speak on most since I did it with NBFuss.