Backend of the WordPress.com [closed]

WordPress certainly can scale. WordPress.com alone served 14.6 billion pages last month. The key is that they had hundreds of servers so that they can widely distribute the load. Since they have a more tightly controlled platform, which helps them ensure that they don’t have badly written code slowing things down. But in the end, a lot of things don’t have a limit to how large they can scale, as long as you give enough resources to it.