Once Voss realized that some of these rappers are nothing but frauds, it became obvious that the art form he loves is turning into a joke.

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Those same people who would call Voss “pretentious” for speaking this way would also most likely call him a “hater” or “critic” for calling out rappers who don’t and never have done what they claim to, when in reality it’s just an honest statement.

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Wikipedia defines “false pretenses” as “when a person obtains property by intentionally misrepresenting a past or existing fact.”
This could apply to hip-hop artists who obtain their wealth by fabricating their past to appeal to a certain market.

A perfect example of this:

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Hip-hop is often divided into two sides: the “blinged out” mainstream side and the “conscious”, “underground” side. The question Voss poses here is challenging the idea that the art form can only be either entertaining or educational, and suggesting emcees blur those lines more often.

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When an emcee says something with some intelligent substance, they are sometimes seen as “arrogant”, “pompous” or “pretentious”, and although sometimes they actually are, there are times when they are merely sharing their knowledge on a particular issue to help educate their listeners.

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the terms “on a high horse” and “on your soapbox” refer to people seen as “self righteous”, complaining about issues that they claim to be above. Some who listen to this song may accuse Voss of being both on a high horse and on his proverbial soap box.
“Soap box opera” is merely a play on “soap opera”, which is something that hip-hop as a whole is often compared to, thanks to bullshit like this:

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When a rapper speaks out against the tomfoolery going on within their art, they are often chastised for it, hence the reference to Chris Rock’s show “Everybody Hates Chris”.

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Hip-hop is compared to prostitution, as the genre is being “pimped”, so to speak, for all it’s worth, making people who are not even a part of the culture rich.

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The majority of today’s hip-hop scene is plagued by unoriginality and empty braggadocio.
Today’s rappers are compared to “witchdoctors”, meaning they may claim to be knowledgeable and adept in their field (music being compared to medicine), but in reality are just saying some bullshit, much how witchdoctors babbled nonsensical “spells” that were proven to do nothing to actually heal their patients.

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