Regarding "ramming ideas" I can see that, but any given conversation is certainly voluntary, so anyone chiming in on a "core belief" in a thread, say, that is debating the veracity of that belief knows what they are getting into.
I agree though, it's not like minds get changed. I see it as less of an e-peen thing than just extemp practice
If nothing else I think that the
better argument threads sharpen arguments. Heck, I've even had my mind changed on rare occasions.