Yes, I agree there are some situations where live conversation is helpful, such as the first two bullet points in your list. I was mainly talking about conversations like the ones described in Kaj's post, where the participants are just "making conversation" and do not have any specific goals in mind.

A good bullshit detector heuristic is usually more than enough to identify claims that can't be taken at face value

I typically find myself wanting to verify every single fact or idea that I hadn't heard of before, and say either "hold on, I need to think about that for a few minutes" or "let me check that on Google/Wikipedia". In actual conversation I'd suppress this because I suspect the other person will quickly find it extremely annoying. I just think to myself "I'll try to remember what he's saying and check it out later", but of course I don't have such a good memory.

You'll rarely be in a situation where your interlocutors are so hostile and deceptive that they would be lying to your face about the evidence they claim to have seen.

It's not that I think people are deceptive but I don't trust their memory and/or judgment. Asking for evidence isn't that helpful because (1) they may have misremembered or misheard from someone else and (2) there may be a lot more evidence in the other direction that they're not aware of and never thought of looking up.

Various signaling elements of live communication are highly entertaining

I think we covered that in an earlier discussion. :)

the environment around you can provide interesting topics for discussion

But why do people find random elements in the environment interesting?