Short answer why you can't use AS for console games is because AS is dependent on the flash player, which is not included in consoles game rendering engine.
Slightly longer answer (regarding web based performance, as mentioned in the js comparison)
Longer still answer
AS is not very appropriate to high performance games because it is not compiled, nor does it run natively. In order for any computing system to handle any code, it has to be broken down into binary for the machine to digest it. In the case of a compiled language, this happens during the compiling process, which results in a script that can be easily read by the machine but looks like gobbledegook to you. The resulting package is no longer directly editable, but is generally optimized for fast performance and will function as optimally as your code was written, within the limitations of the hardware it is running on. An interpreted language uses another program to interpret the code into binary for it using expected patterns during runtime. This could be a plugin, your browser, your OS in some cases, or some other extension designed to interpret the code from what the developer writes into something the machine understands. This way code can be maintained in a human readable format during runtime and usually has pretty good cross platform support if the render engine does(Java is a good example of this, as it can run on any machine that can handle the Java Virtual Machine, which is most everything from your phone to your toaster, well, if you have a really nice toaster anyhow), however there is usually a performance tradeoff. Console games require a lot of complex calculations simultaneously (particularly for 3d playfields and particles) which are beyond the scope of AS, and most other interpreted languages too for that matter within the timeframe that needs to happen to give you a game experience that isn't laggy or choppy. Interpreted languages can also run into problems when your machine is under a heavy load as either the program you are running or the interpreter becoming unresponsive kills your program, as opposed to compiled programs in which case there is no interpreter to make them hang, though the program itself can still hang if there is not sufficient memory to run it.
In college (game design), they basically beat to death the importance of C++ and python too to some degree, as they both perform decently (python's a bit slower but has easier syntax) and interface with rendering software such as Maya and Zbrush. I can't comment on C# as I don't develop in a windows environment and I hate visual studio, but I'm sure it's not incredibly much different from C++ or any other C-based implementation for that matter.