Well, this is basically the essence of the political views of the Free Software movement, according to Mr. Stallman's essays and other statements. Many supporters don't get this, though.
Mr. Stallman repeatedly called proprietary software "unethical" and "immoral", words we usually use to describe theft, rape and murder. If you assume the premise to be true, forbidding proprietary software by law is a rational conclusion. Then, it's just a matter of political power.
From an interview with Mr. Stallman [1]:
"We have a paradoxical situation where one particular area of business [...] uses a particular business practice that's based on subjugating the public, based on dividing and conquering. Well, when there's a business practice that conflicts with an important value like freedom and community, prohibit it."
And further:
(Interviewer): "Should, should all software be free?"
(Mr. Stallman): "Yes."
From a different interview [2]:
"Non-free software is basically antisocial, it subjugates it users, and it should not exist."
Mr. Stallman repeatedly called proprietary software "unethical" and "immoral", words we usually use to describe theft, rape and murder. If you assume the premise to be true, forbidding proprietary software by law is a rational conclusion. Then, it's just a matter of political power.
From an interview with Mr. Stallman [1]:
"We have a paradoxical situation where one particular area of business [...] uses a particular business practice that's based on subjugating the public, based on dividing and conquering. Well, when there's a business practice that conflicts with an important value like freedom and community, prohibit it."
And further:
(Interviewer): "Should, should all software be free?" (Mr. Stallman): "Yes."
From a different interview [2]:
"Non-free software is basically antisocial, it subjugates it users, and it should not exist."
[1] http://www.pigdog.org/interviews/stallman/interview_with_sta... [2] http://www.zmag.org/znet/viewArticle/4795