What is the absolutely worst premise you can come up with for a story? Stupidest, weirdest, most unwritable. Take your pick.
I personally believe that there isn't a premise that isn't unwritable. There's always a way to write something down and make it interesting, all it needs is a fresh perspective to see it from.
But just there's no unwritable premises, there ARE premises that are absolutely PRONE to being fucked up. Like they have inverse potential to being screwed internally. Like a prolapse asshole. There is one premise whose prolapse asshole reaches so far it's become a rectal space elevator to Mars.
That fucking isekai about a smartphone.
A fucking smartphone.
You take the most mundane aspect of modern life and you bring it towards a fantasy world. There's so much potential to it. What if the fantasy world is actually built with codes? What if you can actually hack the system with those codes? What, you think hacking the system is too boring? How about gaming the system? Boss attacks via sound waves? Just turn off the volume. Cave too dark? Turn on the brightness. Use mundane options in common smartphones and deal with problems without outright HACKING everything. Caught by bandits? GPS, bruh. Telepathy? Don't need it, we got Bluetooth.
Somehow or rather, that smartphone isekai anime (I'm not saying the name, it doesn't deserve it) reduced the device's role to a glorified bluescreen. It's literally just a status screen for the MC to press into and spawn shit. Sword? Press something. Dress up? Press something. Money? Press something. Not only did it reduce a smartphone's already dampened potential as an equipment, it reduced it's role to a simple fucking tool. The fucking premise was wasted since episode 2. It somehow saturated the isekai genre FURTHER than its peers.
No, it's not by the virtue of other isekai anime saturating the genre. I'd argue that isekai smartphone anime dug a six foot hole for the whole genre, it's just that the genre was already in a shallow grave; that anime simply finished the job. Pure materialism, pointless growth through a mundane fucking object, and a dead premise murdered by the author's crippling lack of creativity. A fucking mudcrab can shit better premises on a beach. There's more good in a convicted pedophile than this fucking anime. Don't give the pedophile a death sentence; strap them down and force them watch endless reruns of that isekai smartphone anime until they find the iron will to voluntarily shut down their parasympathetic system. Don't worry, the harem is so insufferable the pedophile would wish they stuck with grown adults instead.