Rate (scale 1..5) question type behaves not as in documentation

Reading the documentation, it should be possible to have rate (single line) question (example 1 in documentation here https://docs.moodle.org/34/en/Editing_Questionnaire_questions#Rate_.28scale_1..5.29).

But when you try to "enter a blank space" - you can't since the system wants you to put in some value. This makes us imagine some labels which copy question text for single line rate questions.