Log Out Everywhere Else Option

Hello,
The option at:

Users > Profile > Account Management > Sessions > Log Out Everywhere Else
Below that it says:
Did you lose your phone or leave your account logged in at a public computer? You can log out everywhere else, and stay logged in here.

I am confused with the overall purpose of the above option? Does this strictly function as a security measure, or is there some other type of a convenience factor?

In the event of a site being Hacked, can you use the option above to end all users sessions, or it is still best to change the Security Keys & Salts in wp-config?