Actually I think this is a Bug but since the ability doesn't currently exist, I can't call it that.
I've just noticed that one of our more "inventive" members has deleted 9 of his posts over the past 5 years.
This finding was the result of a review and discussion of one post containig an unverified statement that cause potehtiial professional harm to a medical speciaist.
I thought that we had a selection that limted post deletion to the Owners/moderators.
I think it's very important to have the option to prevent individual member from deleting their own posts because it changes reality.
We are now possibly unable to prove where that particular piece of (probable) misinformation came from.