This is absolutely false in California, please don't spread dangerous misinformation.
See CVC 22400(a):
No person shall drive upon a highway at such a slow speed as to impede or block the normal and reasonable movement of traffic unless the reduced speed is necessary for safe operation, becauseof a grade, or in compliance with law.
No person shall bring a vehicle to a complete stop upon a highway so as to impede or block the normal and reasonable movement of traffic unless the stop is necessary for safe operation or in compliance with law.