Convenience for end-users and avoiding link rot is probably one of the reasons.

Not selfhosted but I think Pocket also falls into that category of service.

While Vaultwarden is great I would not suggest selfhosting your password manager unless you do regular backups. Losing all your password cause your server went down is a great way to ruin your day.

Nextcloud-snap is surprisingly easy to setup. snap install nextcloud is all you need to have a functioning setup. Then run a second command to setup HTTPS and you’re good to go :D