For me, deleting profiles and posts is only justified if they represent a security risk for the person who requests it. There are countries where cryptocurrencies and everything related to them are banned, and someone from such a country would have a good reason to ask for everything to be deleted if they suspected that something bad might happen to them if they were discovered.
However, such requests should be approached individually, because I agree that deleting a large number of posts can leave large gaps in the forum.