Precise laws are usually because enumerating every single bad alternative is an issue, so they just tell you what is permissible. Besides, such specificity is

Precise laws are usually because enumerating every single bad alternative is an issue, so they just tell you what is permissible. Besides, such specificity is usually drawn from building code best practices, which advocate for standardization. Which means that manufacturers don't bother creating radiators with less than six heat settings.