(1) If you're a software developer, then you'd know that ASP.NET is not meant to be used for resource-hungry dynamic webpages. You'd also know that having a server with an ASP.NET back-end on your own machine is a simple test-bed and nothing more. You can construct simple test cases without doing much harm. However, you're generalizing things by only citing one language. Also, anyone can code the example you cited. I can also make a webpage with PHP as a back-end. What's the point you're trying to make, that a MBP can run simple scripts? If that's the case, then, so can just about any computer.
(2) What do you use as your IDE? What do you use as your text-processor? Are you using Xcode, because if you are you'd instantly know that it runs sluggish. Me? I use vim and the command line to write, compile (if applicable), and execute my stuff. This means I can get away with coding things in C/C++/Java/Perl with a low memory footprint. The moment I start to use Xcode or Android Studio, however, resources begin to be gnawed at voraciously.
(3) A proper developer machine can't always rely upon AWS and similar servers because one doesn't always have an internet connection. If you don't have an internet connection, then, obviously you need to have the ability to do things on your own computer.
(4) When it concerns front-end development, how many browsers are you trying to be compatible with? If you're a serious web developer, then, you should know that it requires testing on various versions of IE, Chrome, Opera, Firefox, Safari, even if the browsers *might* share engines (depending on the browser and its iteration). That's called thorough testing and is the mark required by professionals. That means resource-hungry benchmarking and testing.