Still holy people today. St. Hildegarde even made the prophecy that people during our time would long for their days based on the visions she had. I have read a good bit of her writings, they're utterly fascinating. St. Thomas Aquinas is my confirmation saint btw.
Should intellectually curious people be afraid of arguments about, well, anything? It is in the confrontation between dissimilar thoughts that understanding can arise after all, those who just preach to the choir end up neither enlightening nor enlightened. If the argument turned into a pie-throwing contest it would make sense to curtail it. Before that time, not so much.
I meant to reply to this at the time but forgot to come back—sorry.
The kind of conversation you're talking about is desirable and has taken place throughout history, but not on large internet forums. It requires small groups. This is true even when the conversation takes place in public—think Socrates at the agora, or the Federalist Papers, or debates in journals. There may be hundreds or (in electronic media) millions of listeners gathered round, but the number of speakers remains small.
On a large, public, optionally-anonymous internet forum like HN, where anybody can—and will—pipe up with their opinion just because they have one, there is basically zero chance of a conversation on a difficult, divisive topic going deep into new places. Instead it will either dissipate into repetition of conventional opinion or—more likely—turn into a fight along tribal lines. I have a feeling one could model this using statistical mechanics.
Once you understand this, it should be clear that it's not a question of being afraid of arguments or questions about anything. It's about how to operate this place in a way that encourages its strengths while minimizing the worst of its downsides—how to 'let your profits run and cut your losses'. The longer I do this job the more I appreciate McLuhan's "medium is the message" insight. The content that appears here is so deeply conditioned by the size and structure of the forum that I'm tempted to say that other factors are negligible. That would be an exaggeration, but not by as much as one would assume.