Could you tell me the way how to react. For example, on the forum a lot of quality answers. Once the user decides to completely remove them. Let’s say he has 1000 replies. He will systematically remove them. What Is The Reaction? People are often very impulsive. They like today, and gone tomorrow. Such actions can take place.
What’s your take on this mass deletion of valuable information? What will you do? Is there a way to disable to do this?
You can prevent replies being changed after X minutes after publishing.
Search for post edit time limit in your site settings and leaves a few minutes to change or delete the reply, because 
This way you keep the continuity of the old topics, especially if you have many replies.
If users start deleting old topic replies you may lose the sense of the answers of other users, making the topic useless or unmanageable.
Thank you, I missed that. The question is closed.
Users can only delete X posts per day, this is already rate limited. And deletes are always published as intent to delete and take 24 hours to realize.
Also, as the admin you can undelete the posts essential to the conversation, and use edit history to rollback deletions using that.