Imagine this capability existed in the US before miscegenation, or same-sex intercourse, or cannabis use, or concealed carry, were legal/broadly accepted. It could be used to harass non-criminal supporters of these measures(caught a SSM proponent jaywalking!) and prosecute those engaged in the target criminalized activity, preventing movements to legalize these activities from ever gaining momentum. Social mores would become ossified. Perfect prosecution is not desirable in an imperfect world.