I agree with Artemix in most things (but not all), just writing my own response to provide more details.
First of all, in my opinion, (as Artemix already had said) Kamchatka does not have the meaning of a poor "underresourced" place. It just has a meaning of very faraway place. And (again agreeing with Artemix), when people were sent into exile to Kamchatka, - they were not subjected to hard labor. It was not a prison, just far-far distancing the person from the big cities. See, for example, here: exiled people were participating in scientific expeditions, or teaching natives literacy.
It was not economical, I guess, to keep labor camps on Kamchatka, there existed much closer places in Siberia where there was more police presence.
Kamchatka as idiomatic expression means - student desks in the last row in a classroom. This assumes that there are at least 6 rows of desks, so from the last row students may not see well the chalkboard, and do not hear well the presenter in front of the board.
Though, I don't agree with Artemix that pupils were only "exiled" to the last desks. They may well choose this place themselves because they like it - especially on a boring subject. In the last desks they could do whatever they wanted without teacher noticing.
Why other more far places not used as Kamchatka: Кадьяк (Kodiak island) is part of Alaska which was discovered approximately 80 years later (Kamchatka 1651, Alaska 1732) and was not much in the public ear to become an idiom. Fort Ross, California (est. 1808) - even later than Alaska and even less in public ear, I guess. And both places are in America - separated by ocean from continental part of Russia. The desks of the last row are not separated from other desks by any aisle, they are just far.