That's one of many rules in MISRA that originate from antiquated "best practices" from the dark ages that don't actually improve safety. We have it today by way

That's one of many rules in MISRA that originate from antiquated "best practices" from the dark ages that don't actually improve safety. We have it today by way of IEC 61508, which gets it from a book on structured programming called Structured Design. That book didn't recommend banning multiple exit points, but it recommended minimizing them to simplify the control flow graph and said code should minimize the distance between black boxes (bits of code that do something without leaky abstractions and have only one return statement). The IEC authors and MISRA thought the logical extension of that was to make everything have one exit point.