I'm going to call an obscure style as being a flow, approach to content, production aesthetic, etc. that has no children in the mainstream.

Example - Abstract Tribe Unique

Sure there are sing song spitters crossing over, but none of them listened and got inspired by ATU and none of their music sounds like it.
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Big PEMFin H & z's
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"I ain't no entertainer, and ain't trying to be one. I am one thing, a musician." © Miles Davis

"When the music stops he falls back in the abyss."