but it's still OK to shit on his lack of content
Seems incredibly pointless, you're shitting on nothing then, since nothing is produced during the time there is no new episode. Hiatuses although annoying are a consequence of how the manga industry does things. Incredibly long working hours and tight deadlines. While you're younger you might be able to meet most of them, but that's not the case when you're becoming older. You should take into account the switch to digital drawing, also. That probably took a long time until Miura became comfortable with the new technology. Teaching his assistants would have also taken time, and interestingly, he still did not consider them good enough to work alongside with him on Berserk. AFAIK they only helped with small panels and added detail under his supervision.
Like if you're out of gas and working anyway but making no progress and it's clear you aren't really enjoying it but you do nothing to address it that's something you should be criticized for.
It's your speculation whether he enjoyed working on Berserk or not. I don't think it's true he didn't, but just because you love doing something doesn't mean you shouldn't take a break from it.
I could have at least respected the hustle if he just pulled a Yoshihiro Togashi with HxH where he sort of finished an arc
I don't think you realise how disrespectful you're coming across. Neither you, nor I, have any say when the manga should be finished. Since it was continuing with all the hiatuses that means the audience was still there, enjoying a high-quality work.
Just think about the contrast of the characters, their interactions and observations and their call to action differ now. Guts does not act at all like he was previously. Neither does Isidro or Pluck. Even established plot points are completely discarded. Why did Elfhelm creatures disappear? Because they were natives of the island? Why didn't Guts' party disappear then, I thought Isma's mom said that the island considered them to be natives? And especially Pluck who was already a native? Why did Isma disappear and not Pluck? How did Zod appear on the island? The only way possible is if he took the dolmen or branch pathways of the World tree. But it's said that only Griffith and Sonia can guide through them, otherwise the others would be lost. But had he just flown there, somehow not succumbing to exhaustion, how did he even know where it was located?
Whichever way you look at it, Miura took the necessary time to at least make sense of his universe's laws and worked not to contradict them. How characters interact, what they say, what abilities they poses. He wasn't just playing "Idolmaster". The community is so strangely fixated on that it thinks that if he never took it up somehow there would be more Berserk. If he had rushed his work the outcome would have been worse for him as a mangaka. This already happened once before, with the terrible Grunbeld novel.
Besides, you could just consider episode 364 to be a massive cliffhanger. It was probably the beginning of the last third of the Fantasia arc.