How to fix dbus and shell prompt startup delays on SysVinit Debian 10

After installing sysvinit on Debian Buster and rebooting, the startup pauses for a minute or two at Starting system message bus.... And then, when you finally type your login and password and hit enter, bash also freezes for a minute before showing you a prompt.

To fix this, open /etc/nsswitch.conf and find these lines:

passwd:         files systemd
group:          files systemd

Remove systemd and reboot.