I think there is not a hard and fast rule to apply to all posts. It depends on how far astray the thread is going and also whether the original poster cares or not. If someone makes a post such as "what do you think about ECT?" then to me it does not sound like a call for support. They just want information and I would think all informed opinions and experiences would be welcome. If, on the other hand, the OP posts "I just had ECT yesterday and I feel great," and people start chiming in "well, you made a big mistake, you will probably suffer permanent memory loss and be less intelligent than before", well, IMO, that is not supportive and should not be in the thread!

So, I think it depends on the situation and the intent of the original post. Use your judgement and if in doubt, PM the poster and ask.

Good question!