Advanced information architecture
This is one area were so far the DIY / "build you own" hosted website companies are unable to compete with bespoke websites...
The ability to add information into your website and for it to automatically be displayed as needed throughout the website.
Currently for DIY website solutions this can only be done manually and with very limited scope, page by page. Whereas with a bespoke website once it is all set up by the developer, it is easy for the website admin person to add information. How the information / content is displayed is automatically taken care of.
Also any changes can be done globally - saving loads of time.
I'll add an example soon but meanwhile I hope you get the gist.