When configuring new Lifecycle Definitions, there are {typically, on average} 1 to 3 transitions out of each state that are needed. The default behavior is "No restrictions on this transition". Which means that more time is spent configuring the transitions that we don't want (edit transition, security tab, uncheck "No restrictions on this transition", Add, select member 'everyone', Add to current members, change permission to 'Deny', Ok) than the transitions we do want. This is especially crucial when the lifecycle definition has many states.
The toggle option (between 'no restriction' to 'everyone denied') would simply let the admin turn off that transition in one step!
No Restrictions (default)
Everyone Denied (selected)