It’s not about whether something is of national importance. Crime is of national importance, but the federal government is denied a general police power. Education is of national importance but local control is paramount in our system. The real issue is whether a problem is better handled with many governments trying things their way, taking into account local culture and economics, or whether a single standard is preferable.
If it was all about whether something was of national importance, we’d have a national DMV and federal grocery stores.
That’s my point. The private sector does some really important, vital things. The fact that they are important and a national interest doesn’t mean government needs to do them at all.