Even those side action characters get sidelined in final battles. Like, in Luke Cage, Misty wasn't really a participant in the season 1 climactic street brawl between Luke and Diamondback and was more doing crowd control. In The Punisher season 1, the carousel showdown saw Madani get shot in the head pretty early on and taken out of the fight. In Iron Fist season 1, we had Colleen deal with Harold's bodyguards while Danny faced Harold off one-on-one. In Iron Fist season 2, we had a role reversal where the duel of Iron Fists at the end wasn't Davos vs. Danny but Davos vs. Danny's girlfriend (which I know a few weren't happy about).
I'll admit, though, yeah, it'd be contrived to find a way to get Karen and Foggy to be there actively participating in the final battle without it just making things messier.