That's one of the dead-ends. They only had so many episodes and they had to prioritize who gets the most screentime. That's what Hollyhock got. Yeah, I also feel that the whole Penny story is rather unfinished(seeing how her mother warned her about not getting involved), and that Hollyhock was given the "easy way out". Obviously she was already aware of S6E8, and probably has seen both interviews, but... When the show introduced her, it made it very clear that she IS Horseman. Of all the characters - she was the closest to someone understanding him, because she is also a mean, fat slob at her core. If the show had time - these sentiments could very well be illustrated properly, but they've settled for the letter. Honestly... season 6 should've had just 12 episodes that would culimate with the interviews. The true fallout would take an entire season 7. But they had to cram it all into 8 episodes, that's what we got.
"Both shows have super unlikable important characters that get no character development and never get punished for their actions." Yeah I'm gonna stop you right there, chief.
I think it was rushed. I mean, I loved it and it was a good sendaway, but... Season 5 already felt more like a filler, I didn't quite feel the whole Philbert thing, it almsot like they wanted to tell more in Season 6, and then they got the note from Netflix. S6Part 1 leaves you at one of the most precarious cliffhangers and Part 2 serves only to... end it. Plenty of history is touched, even "re-touched", but there are many things that are just left.... hanging. I won't list them here for obvious spoiler reasons, but... Nah, it's impossible to say anything without spoiling, and this show deserves better. What's done is done, Netflix is Netflix, and 2020 is 2020. There is no room for Bojack in our world, and no point to argue what could've been done better. Because what was done... was done marvelously. Not every work of art needs to be a franchise, and not every franchise is a work of art. Bojack ended as a work of art. The rest is up to us.