[asher]

>Where are the apps that are even half as feature-rich as a typical Windows application from the '90s?

I hear you. One reason for this is scalability. You can build richer web apps if you aren't shooting for scale.

I worked on two startups with conventional LAMP stacks and heavy user sessions before joining Yahoo. At Yahoo there was really no session object[1], due to scalability. A few cookies could be set to customize behavior, but adding new cookies was seriously frowned upon. This made me appreciate sessions as a means to adding in nice little features.

In principle you can solve that by storing the session in a scalable key-value store, providing the latency is low enough.

[1]Generalization only valid for the properties I was exposed to at Yahoo.