Spinster school teacher was nothing ground breaking.  Mary Richards went to bat be for equal pay as the only woman in an all male newsroom.  MTM not only reflected demographic social change, episodes explicitly addressed issues of equality.  Just watched the pilot again, opening with Mary, Rhoda, Phyllis & Bess.  Each character would go on to depict individual & social change, two of them in primetime spin-offs.  Even Bess went to bat for equality when Mary picked up a handsome stranger, 30-something goood girl Mary was on the pill and had overnight dates.  At the end of each show audiences were reminded Moore owned her show, directly inspiring Oprah's Harpo.  When all is said & done, Mary may have been the most influential feminist of the '70's, even if Moore never donned the mantle herself.