I always judge such visualizations by the quality of songs they select for certain genres.
I can say their selections for Prog Metal are on point, even if the specific songs by those bands would not have been my choices. Even if I find their positioning of Kamelot as Power Metal and Symphony X as Prog Metal both slightly suspect (both are more symphonic metal, hell Symphony X is almost the genesis of modern symphonic metal, picking up from Yngwie).
Already seems flawed, they seem to have only minor connection between post-punk to goth/darkwave. Like they put Joy Division and Killing Joke under Post-Punk but Red Lorry Yellow Lorry and the Mission under Darkwave, and Bauhaus, The Cure and Siouxsie and the Banshees under Gothic Rock. Then like all the bands in their Industrial Rock playlist are inspired by Killing Joke but that’s over in Post-Punk.
The first one, the Musicmap. Not gonna drag the research down because I find the playlists a little weak, though. It’s a really fun page, and I finally learned all the different techno genres. “Gabber” was a real genre, for instance. :)