Sure, I could pick any language and learn it as a first time programmer (essentially). I could learn Haskell as a first time developer too. But should I? Comparing Arc to Python is not only a comparison of syntax and coding style, which by any means is a minute detail in this case seeing as they are both easy to grasp and relatively succinct, but a comparison of resources and community as well. Python for example is the language of choice at many schools and universities for first time programmers. The community is much larger and more developed. There are many more resources for python that I can find and know of than for Arc.

Arc might be a powerful language, but I find little reason to choose it over Python, Java, JavaScript, etc.