@Meanlucario
Because they’ve been around since the first season and each have a dozen plus individual episodes.
I don’t see Starlight getting more episodes than she did last season so she’ll maybe get somewhere around 2-6 episodes. We know she’s in the first episode, but that it’ll mostly be about Twilight trying to figure out what the hell to do with her.
The second episode the Mane 6 leave, and she and Trixie have missing map shenanigans.
So after that she might get 2 more episodes and maybe the finale will be about her too. And again it’ll be wrapped around either her training with Twilight or if they go with her being ready to “graduate for reals” at the end of the season, it’ll probably have her paired with some new character or Chrysalis comes back for revenge.
I don’t see Starlight interacting much with the Mane 6 now that she has her own group of characters (Trixie, Sunburst, Discord) to work off of for that cheap Brony pop.