I think "cannot do" is a misnomer. Shouldn't it be, "consciously designed not to do"?
Server-side state management offers several advantages over in-browser state management, such as:
• Better security and privacy.
• More reliability and control.
• Better and more predictable performance since it removes the burden from the client device.
• More accurate user metrics.
• Minimizes browser compatibility issues.
• Better scalability when prioritizing user data security.
• Easier debugging.
(Edited to fix bullet formatting.)
It does offer advantages, but also disadvantages. Lustre lets the programmer pick whichever technique is most suited to each component in their user interface.