Since Witch House describes everything from Mater Suspiria Vision to You Love Her Coz She's Dead now, it might as well apply to this too. As a label, it's expanded into meaninglessness the same way goth did, but much faster. So it goes with genres that describe an aesthetic or scene more than the form of the music. It really would be more convenient if we'd just say "malcontents who like three or more of: electronics, red, black, purple, spooky imagery, reverberation, minor scales, extended vocal techniques, distortion, or clipping, please stand on the left."
As a sound the drums reminded me a bit of oOoOO, hence why I said that. However, you bring up a very interesting - microgenres. Goth notwithstanding, it's hard for a genre like witch house, chillwave, vaporwave, and other microgenres to hold up and maintain whatever meaning they started with. As soon as more people become aware of the sound everything gets distorted and it's hard to hold up when the base of these genres are already flimsy at best.