I want to know why Python is not fully object-oriented. For example, it does not support private, public, protected access level modifiers.
What are the advantages and disadvantages of this? By these expressions, Python is suitable for what applications (Desktop, Scientific, Web or other)?
I believe Python is more of a very practical, pragmatic language. 
Concepts which offer value to the developer are put in, without too much consideration about theological concepts like "proper OO design" and stuff. It's a language for people who have real work to do.
I think Python is suitable for all kinds of environments, though Desktop is a bit difficult due to the lack of a single framework. For all applications it's handy to use a framework,
like NumPy for computational stuff, Twisted or Django for web stuff, and WxWidgets or other for Desktop stuff.
Why is Python not fully object-oriented?