Digesting the many white rappers has been a on-going trend since the late 2000's - maybe earlier as there is always a white male or female endured by the craft of hip hop.
Of course, the Hip Hop culture has legendary white rappers who respect the craft, like Eminem, Logic, or Mac Miller. Although, the list of known and cherish White rappers is unfortunately skim.
The reason for this is up to perspective. Although, one of the main contributions to the hip hop culture is the idea that there is always been a specific story being told within the music. For the most legendary rappers in the second stages of hip hop, like LL Cool J, Public Enemy, and Tribe Called Quest, discussed the violent lifestyles and unjust conditions of black Americans. This stigma continued and hip hop transformed into a powerful sense of speech and way to fight back the oppressive notions located among the American society.
The 2000's came seeing the "cool vibes", listening to the "dope beats", or simply perceiving what significant power the hip hop culture carried, other cultures wanted to join. One of the most predominant races intrigued by the rap game were white Americans. Now no doubt, some rappers, like Eminem, told a real story but others like Miley Cyrus, Justin Bieber, Katy Perry, and now Post Malone, used the platform as self centered tool and possible joke. All for the intent to get more clout or for a certain amount of fans and fame.
Before Miley's transformation:
After...
This transformation lasted for about three years and in turn, Miley made tons of controversy and money. Although, after the fame decreased, she declared hip hop as "degrading" and moved back into country Miley.
Same with Katy Perry, who repetitively uses the Hip Hop's style, like grills, certain dance moves, and sayings, in order to boast her reputation.
And Justin Bieber...
The start of his career:
After he needed a "different route":
Now we have Post Malone, who after a good amount of years of rapping and using Hip Hop for the main source of his career, decided to declare rap has "not emotional enough", "degrading to females", and "lacks depth or meaning". That's one perspective, but Post Malone, your entire career was built of this culture. Which in fact, is not just about females or smoking weed. Why the sudden change?
It's one thing to copy someone's style, but to use such a predominant and significant culture like Hip hop, which has transformed both the black and music community, is not only disrespectful to the craft, but disrespectful to the people who started and continue to ride for Hip Hop.
For the Hip Hop culture didn't pop off because of the dope beats, sets or because of the "Female attention", the culture became something because it represented a voice for the black community. During certain times, including today, music and art seems to be one of the main significant factors to help spread a story. A story that not only gives a voice to many impoverished communities, but a story that needed to be communicated to the inclusive American world that ignored the black community needs for centuries.