sys password change in data guard broker environment

Team, As per best practices in "Data Guard Physical Standby Changing the SYS password when a broker configuration exists(1199943.1)", we should be disabling the redo transport before sys password should be changed and password file should be copied from primary to standby.

I wanted to understand why we need to disable the redo transport services. As per my tests, I can see that shipping continues even the sys password got changed on primary. This is for obvious reason as existing sys connection to standby remains valid. We require new password file only when standby goes down and so redo transport services require to have fresh sys connections to standby.