Lots of songs to bring back good memories. But I am curious about what their criteria happened to be. There are a few artists that would not be categorized as “One Hit Wonders” such as Devo, Don Williams, Mickey Gillie, Emylou Harris, Donald Fagen, etc.
One-hit-wonder lists usually say more about the compilers own lack of knowledge than they do about the music business.
That said, there ARE actually one-hit-wonders, just a lot fewer of them than a lot of writers imagine.
Billboard has a myriad of different lists, including R&B, country, and rock.
As in your example, Emmylou Harris has many, many hit songs; however, they were hits on the Billboard Country chart and (with the one exception) not the pop chart.
So she's a 'One Hit Wonder" according to the criteria on which this list is based, as are many country singers with multiple Top 40 Country hits but only one Top 40 pop song.