Server side code must be very productive to handle large amounts of data and visitors. Of course, php is not the fastest language, but sure have the best value on market. Pure php is fast enough not to complain, especially with php7 announce. PHP frameworks are huge libraries for developers; they automate a lot of routines and enforce developers to code under framework's standards. Nowadays to write backend code without framework is long and expensive process. Sometimes it’s better to write custom code without any 3rd side frameworks, but it is only for very serious and unique solutions.
Binboro want to annonce that our team started to use emberjs as default framework for front end. All our applications will be based on it. As development company we pick frameworks very seriously. We can not switch them often and need to build solid workflow all over the team. So we spend time to pick best according our requirements.