Nobody in 1860 existed in an 'echo chamber,' bombarded with the same message from multiple sources multiple times a day, every day, with precision coordination. It couldn't be done. The technology simply didn't exist. It's a moot point.

It's not a moot point. That voter in 1860 was just as ill-informed - probably more ill-informed - than voters today.

You didn't need to bombard them with the same message multiple times a day. The typical voter would have a head filled with misinformation to begin with - by 1860, you had near-universal white male suffrage, so your typical voter would certainly have materially less than a high school education (though by then, there's a better than even chance that they might be literate). Their knowledge of the world and the facts relating to public policy issues would have been miniscule at best. The typical modern voter - yes, even the typical modern Fox-watchin' and Facebook-usin' voter - would have a more accurate understanding of the world and how it works and the issues of the day than your typical 1860's voter.

The 'echo chamber' and technology just makes the ignorance and misinformation different. It doesn't mean that there wasn't just as much, if not more, ignorance and misinformation among the 1860 electorate as there is today.