Are you developing Php applications using OOP paradigm?

Of Course , 

Yes i have been developing application using Object Oriented Programming. Recently the application i am working on (Development and maintainence) is Degree Attestation System comonly known as DAS in pakistan which was purely developed in object oriented PHP language.

Yes, i am. i work using CI as framework and works on OOP paradigm

Yes. I am developing applications using CodeIgniter framework and every php framework works on OOP paradigm.

Yes, I do:

• I write WordPress plugin in OO PHP
• I use Laravel or Slim frameworks
• And of course, Javascript

Yes, i use PHP PDO which is a core-PHP and is purely object oriented

Yes oop paradign is better to have high scalability for your PHP applications. But still i recommend to use any of the MVC frameworks like Codeigniter / Yii / Drupal / Zend etc.

All the above follow oops internally and using Model-View-Controller method, as a result all tehse have high modularity and scalability. As these have high performance pre defioned functions inside this for templating and for data access from databases its very easy to implement rather than writing all those codes from scratch and your application wont be having any kinda repetitve codes. Also for highly used functionalities like login, emailing etc if you create a library then definitely you can use it across application which will definitely cut down your development costs day by day / project by project

Yes offcourse, but don't know why if found simple structured programming more better than that.