Because there is a LOT of political mileage to be had in purveying this stuff, and nobody remembers who pushed it when it not only fails but is found to be counterproductive.
IMHO any politician who hangs his hat today on "being tough on sex offenders" has no real issues, much less solutions to same, on which to run. All he can do is pander, pander, pander.
I had hopes for Bobby Jindal, but he's falling way short. Some folks tell me he's a "big-government Republican" but I think that's a contradiction in terms.
I think you're still laboring under the misapprehension that "conservative" and "Republican" are synonyms.