Too many uninteresting side characters taking up too much space in the story. I don't care about the punk guy or the delinquent he met two minutes ago -- or the LMC's vice president for that matter. I'd much prefer if the narrative refocus on the band members.
I think you can't focus on the band members ignoring the side characters, because there's no real plot without them.
They don't have some big goal they're chasing or some overarching story arcs imo.
It's pretty much just performing at the next event xy with the twists stemming from their interactions with said side characters.
If you get rid of most of the side characters, you're left with the Heartbreak - Protocol rivalry & the relationship between the bands' members. Which works I guess, but there's nothing really out of the ordinary happening there.
In general, I feel like the story is about the whole LMC experience viewed primarily from one specific band's perspective, but you need members to make the thing feel authentic.
Although I feel the pain trying to keep up with all the characters appearing in passing...