It is idiotic to put no time limit on this feature. A few days or week might be fine, though most online forums it is only a few hours as far as I have seen.
Lacking a quote feature, this will make for too many confusing threads when there are deleted posts. Leaving a heading and notice of a deletion means nothing.
These boards used to be a valuable resource years after original conversations took place. But now that can all be destroyed.
Why should users waste their time with lengthy and knowledgeable replies thinking the conversation can help people in the future when others in the thread can just delete their posts when they get mad at Acom or RW. They now will be better off only replying to RW mail lists with perhaps a short note on the parallel message board directing others that way.
A potentially good feature with the usual poor execution due to not discussing this here with all users in advance.