I almost miss this setting.
I think, its a good idea to give an information in user interface. So they will have no misunderstood about this draft feature.
At 180 days, it would only make sense if it were being deleted while the user is editing it. But anyone who doesn’t finish their draft in 180 days probably doesn’t need it and probably doesn’t need to be told about it. If they haven’t composed a new post in 180 days then they’re hardly likely to care that they’ve lost a draft post.
If the site admin sets it to something really short, even 1 day, then I’d say this then becomes a feature that would have to be explained and justified for that forum only.