I have gone through hundreds of articles and blog posts that saying WebMatrix is just for beginners and such. my question is, why shouldn\'t I use WebMatrix to create a real-wor
Some people think that all "real world" apps are gargantuan sprawling things that need massive architecture, multiple devs in teams, source controls, tests etc, etc. Those types of apps would not be suitable for WebMatrix. Millions of real world apps do actually take the shape of lightweight Q & A sites, blogs etc, and are built and maintained by one person. You can certainly build these using WebMatrix.
Tip for the future: if loads of people blog saying "Don't do X" but don't explain why, you can be pretty sure that they haven't got a clue what they are talking about. For some reason, WebMatrix has attracted the attention of lots of those type of people...
I don't see why not. It's basically just an IDE. The code you write will still be ASP.NET. It will still run on IIS. You could write a "real world website" on notepad if you were so inclined. It might be a bit harder, but if the website is simple enough it's definitely doable. What might make or break your website is your design, and you don't really need an IDE for that.
I highly recommend you listen to a recent Hanselminutes episode (http://www.hanselminutes.com/default.aspx?showID=268) where Scott Hanselman and Rob Conery discuss WebMatrix and their experiences building a real-world website.