We live in a world that recognizes the open source, performance-oriented, single page applications (reducing server round trips) as professional applications. Microsoft was too comfortable to move beyond server-side development. Later, they started experimenting client-side validations mainly, thanks to MVC2. Now, with MVC Core, they're back in the game!
This brings us to the million dollar question—is the client-side programming really safe? How long will it take for the hacker to break the client-side validation and get into the server? In today's world, even a dummy who has just started to learn how to hack could do that in minutes. To be blunt, we have no control on the client, and we cannot blindly trust the data we receive from the client (which could be hacked/injected by anybody using tools such as Fiddler...
