vsftpd user setup missing element:

[RSabounds]

https://docs.rackspace.com/support/how-to/rackspace-cloud-essentials-centos-configuring-a-user-in-vsftpd

document doesn't inform of a necessary change for functionality.
first:
it's unclear if the document recommends '/bin/false' vs '/sbin/nologin'
second:
with default vsftpd, pam configuration enables a requirement for the shell to be listed in '/etc/shells'
This document, fails to mention need to add this value.
Without it, I found that only if the user has default shell could they login.