There's also the issue of of near discovering the notebook, looting it from the vault, making a perfectly indistinguishable 1:1 copy, and planting it back in the vault, all in the span of less than a single night.
The fight between light and L felt intresting because its shit any normal person could reasonably come up with and when you DO see it, you feel cleverer and its something you could reasonable apply in everyday life in similar sitiuations.
Like when L worked out light was a student based on the scedule of killings lining up with a japanese student's schedule that was insanely clever.
It makes sense, its not a far fetch, and it doesn't require unreal intellect or money to work out, its just clever deduction.
But "I made a carbon copy of a book with thousands (if not tens of thousands) of names, overnight after looting it and planting it from a bank offscreen while you weren't watching" is pure bullshit because at that point you basically have fucking superpowers.