[slashdave]

Because browsers are being used as application frameworks (i.e. for making applications) rather than what they were designed for.

[dariusj18]

The dream has long been to have code distributed to thin clients while allowing intensive tasks to be run on servers.

[shadowgovt]

That's one dream. There are advantages to thick clients as well... less network traffic if the device can do processing on site, A much easier to maintain and update distribution model over the traditional desktop experience for what is essentially application software, etc.