Most field types can be set with a blank default, but not Yes/No fields. In my use case, I'd like to force users creating a new record to affirmatively indicate the starting state of a Yes/No field. Marking the field as required doesn't achieve this because the field's default state is already either Yes or No, which means that validation doesn't flag the field as missing data when users try to save.
Example:
I have a Yes/No field called "Is a Contract Required?" This is a question where the answer is a binary, so I didn't opt to use a Single Select field. I also like the heightened visibility of the Yes/No field for grid and other views compared to the way Single Selects display. The field defaults to No because most of my records do not require a contract and, more importantly, because I have no "User Input Required" option for the default that would leave the field blank until I enter Yes or No when creating or updating a record.
I'm entering data for a new record, and since the default for this field is No it becomes habit to ignore the Contract Required field, which is usually set to the correct option. Then I encounter an item that does need a contract. I should mark the Contract Required field as Yes, but because I've been effectively skipping the field for some time, I reflexively do so again. Now my record says it does not require a contract when it in fact does.
I have automations keying off this field when it is set to Yes, and for this record, those automations do not run. A contract record is not created, assignments don't get made, notifications don't go out. We risk inadvertently proceeding without a contract for the work associated with this record.