Why $ORACLE_HOME/bin/dbstart or dbshut does nothing?

On a Single Instance Standalone Database, If you want to stop/start everything that runs on a ORACLE_HOME, you can run this:

[oracle@olinux8 ~]$  $ORACLE_HOME/bin/dbshut $ORACLE_HOME
or 
[oracle@olinux8 ~]$  $ORACLE_HOME/bin/dbstart $ORACLE_HOME

But why sometimes it does nothing?

[oracle@olinux8 ~]$  $ORACLE_HOME/bin/dbshut $ORACLE_HOME
[oracle@olinux8 ~]$ 

Well.. .this is where the magic of N or Y at the end of the line in /etc/oratab.

[oracle@olinux8oem ~]$ grep oemdb /etc/oratab
oemdb:/u01/app/oracle/product/19c/db_home1:N
[oracle@olinux8oem ~]$

Just change to Y and process will stop/start DB and listeners.