So I'm fighting this giant eyeball.
I don't know why it's an eyeball—I guess it's a demon or something, but I don't know why it takes the shape of a giant eyeball—or why it's surrounded by colored tiles, or why it keeps emitting clouds of fog. All I know is that it's in front of me, and I have to beat it, and in order to do that I have to spend around 20, 30, maybe even 45 minutes directing my characters to attack, heal, and boost their defense with the right abilities at the right times.
Once I defeat this eyeball, I'll be rewarded with some dialogue. A cut-scene, maybe. More of the story, and more dungeons to plow through. More things to do.
So I keep fighting.
We've been conditioned to accept a lot of absurd things in video games—weapons clipping through walls, NPCs repeating the same lines every time you talk to them, nobody batting an eyelash as you steal from their dressers—but none are as absurd as the JRPG boss fight.