That's because the underlying assumptions are false. Being religious doesn't require one to be "clueless about rationality" and supporting SOPA doesn't requre the supporter to be clueless about technology -- they may as well hope to benefit from breaking the Internet.
As every regulation (the more severe, the better) it will give an advantage to established companies over startups and newcomers, maybe even allow the former to became gate-keepers of the Internet business; DMCA allowed for attempts at censorship (silencing criticism by claiming trademarks), SOPA will take it to a whole new level; supporting SOPA signals loyalty to the entertainment industry; etc.