I think the time frame you’re looking at there is a bit key to why things may have changed.
Prior to the 60’s the Southern, conservative, racist leg of the Democratic party hadn’t split off and been swallowed by the GOP. And 1996 was about when the post 70’s national rightward swing had peaked and Democrats started to gain some electoral success as a result of their growing center right faction.
At the same time you have both the erosion of Unions and the erosion of support for Democrats among certain kinds of union members, farmers and so forth.
The second half of that might be what puts the lie to “can’t”. I find it hard to believe that a candidate along the lines PA’s John Fetterman couldn’t make waves there. Given a lot of that guy’s base is in parts of PA that look an awful lot like West Virginia and among the same sort of coal and natural gas workers and white union laborers that are supposedly the stumbling block in WV.
It’s a little ridiculous to say there’s no way to make in roads in that environment, when some one is.