There's a lot of well-preserved documents, debates, and critical discussions from those periods, but most of those are preserved because they were among elites in the academy or political spheres.
I find it hard to believe the average person in 1925 was more informed or even able to think critically about national and international politics than someone today. It certainly wasn't as if there weren't powerful people who controlled most of the news and communications back then either.
So, the effects of our citizens not being able to reason effectively are more impactful/destructive.
You mentioned that 100 years ago, there was one source of news. This underscores my point. Sure, that's not ideal, but even pernicious effects were somewhat self-limiting versus a frequently hostile, 24/7 technology-fueled infospace, featuring hostile actors—known and unknown—who are out to destroy the fabric of our society.
I mean, any actor—including state adversaries—can essentially run military-grade psyops on our population. In a "stable" environment, an inability to think critically is somewhat buffered and fallout is limited. But, in a hostile information space—intent on manipulating subjects for the destruction of their society—it's catastrophic.