NYT and the Commerce Clause

The New York Times' editorial on the commerce clause offer no legal reasoning to support the commerce clause. Basically, they say that a lot of great laws that are beneficial to society are based on the commerce clause so we can't ever limit it. Why have a constitution? If laws are beneficial, forget about whether the government is empowered to pass them. In one example, cited by the Times, Elena Kagan as Solicitor General argued that confining sex offenders after their sentence has run could be justified by the Commerce Clause. Whatever the merits of keeping sex offenders behind bars, what does it have to do with commerce? Stretching the meanings of words so far that they lose all meaning makes having a constitution meaningless.