An ounce of prevention is worth a pound of cure.
Back in 1922 when I was young I was told that is the only to look at doing home repair projects.
If you have a older home, the poly barrier is considered the same as the kraft-faced insulation, just tightens up any chance of air movement.
There has been issues of walls "sweating" in regards to the poly barriers ontop of kraft faced but that was limited to super airtight homes, tyvek outside house wrapped and the fear of radon exposure in the home.
If you have an older home, more than likely the house has enough openings that allows the house to breath which is considered better in some circumstances. < That statement right there alone has probably saved lives with homeowners with leaking heat exchangers in furnaces that are emitting Carbon Monoxide.