That kind of thing is a gold mine for data harvesting. Automatically: for each comment from a certain state, go through their commenting history to map opinions

That kind of thing is a gold mine for data harvesting. Automatically: for each comment from a certain state, go through their commenting history to map opinions on whatever you care to search for on a state-by-state level. Way cheaper and faster than phone surveys, and also gives a radically higher value slice of the population (than those who would pick up the phone to answer a survey). And that's probably the least nefarious thing someone could do with that data.