That isn't true. PHP is a general purpose programming language. Binary manipulation is done about as often with PHP as it is with ruby. PHP has pack and unpack functions. Binary data can be stored in a PHP string with little overhead.

Also in practice PHP has been weak at certain types of string manipulation, because the template language doesn't lend itself to capturing the output in order to filter it. Intermediate PHP developers know how to save buffered data, but it isn't as straightforward as manipulating output data with rack or wsgi middleware.