OOPHP is an approach of "include and reuse". Objects simplify web development by eliminating the need of cut, paste and adopt existing code. So as far as principle of programing languages is considered OOPHP will provide us some advanced features of php like reusability inheritance etc etc.
Speaking Specifically,
One of the new classes included in OOPHP like SimpleXMLElement class. With this class you can incorporate RSS feeds into a web page using very few lines of code. Additionally without a minimal understanding of the masics of OOPHP, you can use full use of the capabilities of PHP5. For instance, If you want to create SOAP client, there is a no other way to do it than by using the SOAPClient class. There is a no need that once you start programming using OO approach you need to always code in this way. OOPHP approach can be used when you want because we can use FULL functional PHP5 by this approach.