not only for mods, but for the author itself.
so, a useful thing to do with this feature is lock posts which already got more than 15 or 20 replies (dont ask me why)
and for the author is just for avoiding hate and stuff (ik this could be easily abused but if so just make this feature possible to staff members)

Well then just dont post anything that youll regret

how ill know what i will and what i will not regret?

Hmmmm

Maybe they should add that