The majority of web developers do use WordPress to build websites, BUT not all websites. WordPress is an excellent solution for creating specific types of websites, but it may miserably fail if not used as intended. It is only the experienced web developer who really knows when to use WordPress or not.
The majority of experienced web developers use WordPress to build websites. Web developers should avoid using WordPress to build custom web applications. Web developers are required to learn at least how to use WordPress. Professional web developers choose their techniques based on the client's requirements.