Why do some coding rules change the order of conditions in PHP if / else?

Some coding guidelines indicate that you should put the variable that you are testing at the end of the condition:

// Incorrect
if($isSomething === FALSE) { // Do something }

// Correct
if(FALSE === $isSomething) { // Do something }

I know that some programmers have a bad habit of initializing variables in such conditions:

if($results = $db->getResults() { // Do something if results exist }

Therefore, the only reason I could suggest that this contradictory rule is to prevent incorrect reinvaluation if you accidentally use only one equal sign (=) instead of two in PHP.

Are there any other reasons?