он сам всё сказал

De Icaza takes the view that the main benefit of .NET is in productivity. "The development model in ASP.NET is lighter than the development model with J2EE. J2EE has taken this approach of Model-View-Controller, which is a beautiful thing from an academic perspective, but it does add a burden. At Ximian we consulted with a number of software companies. They said, ‘We can develop applications 20 to 25% faster than with ASP.NET than we can with J2EE.’ Developers like ASP.NET because you don’t have these three layers of Model-View-Controller. Instead there is the presentation layer, and the model is the database. You don’t have this intermediate layer."

и дальше

What is clear is that Mono (as opposed to .NET) is not currently designed for scalability or transactional distributed applications.

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