Why is it not recommended to use single page interface for public websites? Now-a-days search engines are capable to crawling SPI sites with proper web page design.
Is there any other reason?
This is less a stackoverflow question and more a discussion forum question, but something that comes to mind is the concept of websites that "break the back button".
For large websites, single page application design is difficult because giving users a range of functionality and interactivity coupled with the ability to move fluidly back and forth between states often introduces problems. A user has to hit the back button 95 times to leave the site, or hits the back button once expecting to go "back" within the application and instead leaves the site and loses their state unexpectedly.
It's great in theory but difficult in practice.