On one of the threads in the gambling section someone asked about investing 100 btc, to which I replied with what most would consider a very reasonable advise. Within literally 30 or 40 seconds, my reply was deleted. I believe allowing this is extremely harmful and misleads readers into believe they are viewing a balanced discussion, which is especially dangerous when it comes to things like other sites and services.

As a form of spam protection, I would support the ability of self-moderated thread creators to minimise-by-default someones reply -- but allowing outright deletion seems like a very harmful policy.