Instant deployment and obsolescence is the same sentence. Do you not see the contradiction? Also, how on earth does the web not have a separation of concerns between business logic and UI?
I am not sure what your point is. Instant deployment is an advantage of web architecture: you have nothing to do on the user device for them to use the new version of your software (barring some rare issues with browser cache).
On the other hand, so far at least, a web application does not age so well at the timescale of enterprise software (an application will live 10-30 years in a company). So we have an obsolescence problem often, i.e. a 5+ years old application will need to be rebuilt to use more modern technology, often at a high cost.
Originally, web architecture mixed in web pages presentation and business data, a result of an hypertext architecture being used for transactional software it was not aimed at at the beginning. Sure, there have been billion of dollars of investment in web technology since then and a lot of things have improved. However, I have the strong feeling things are still messed-up, especially for developments 'in the wild' for team who do not have strong architecture skills.
