Good that they actually raise the question of users not wanting to be archived. I think the semi-ephemerality of channel based systems like Discord is increasingly popular partly because of various sorts of "cancel wars", well- or ill-intentioned capture and use of posts out of context.

Semi-ephemeral is the wrong way to view Discord et al. It's only that way if you actively remove your messages after a while, but they have made it as difficult as possible.

Though the fact that it's hard to archive too, perhaps make it more ephemeral on the whole, since few people will have a backup when do you get around to remove it.