Digital BW, The Print

I was wondering how people package matted prints for sale.  I've always hinged my prints to the mat and not the backer because then the photo is always aligned in the mat.  That also means there's no need to hinge the mat to the mounting board. The sandwich can then go into a tightly fitted plastic bag that holds it all together for sale.  I've heard it said the print should be hinged to the mounting board when selling matted prints.  I just don't see why.  Any opinions?
Thanks 
Granger