While musical tastes are 100% subjective and purely matters of personal taste, assessing technical musical talent is far less so.
It's fine to like Mariah Carey and for her to be a person's "favorite" artist... the only criticism that can be given to that statement would be purely a personal attack on the posters opinion/tastes.
However comparing pop-star Mariah Carey's actual influence on music or her composing skills to Bach or Mozart (or the likes of the Beatles, Nirvana, Michael Jackson & maybe even Madonna!) is laughable sorry.
EDIT: Lets see how many Mariah Carey songs beyond maybe that heinous X'mas "meme-song" ANYONE recalls in any way 50 years from now. (The Beatles have their own dedicated Sirius/XM channel plus still get DAILY radio-play on FM and extensive streaming)
I listen to music like I do with Mozart. Out of historical context because I'm late to the show. Therefore, it is predominantly the arrangement of notes themselves that make it a yes or no.
She impacted the music world like Beethoven. The ones exposed to her are inspired and tried to emulate the initial master.
The rapper+singer collab has become part and parcel, much like the scherzo became acceptable and standard operating procedure from his/her time onwards.
The music of Mozart is the most difficult of all to comprehend due to the simplicity and leanness of what is present in the score. You're So Cold, as a musical effort, brings the 18th century into the last decade of the 20th, using two of the simplest yet effective features of "Mozartean features", the "Mannheim sigh" and the rhythm of an 8th rest followed by three eight notes and then a final note on the beat. Before you condemn based on period alone, the efforts of the likes of Perahia, Barenboim, etc to write candenzas for Mozart concertos can be generally deemed noble efforts, but utter musical failures that simply could not emulate the master. Only Geza Anda seems to have some sense of musicality...
Mozart's lane includes opera, of which coloratura and fioritura was expected and demanded from both the men and women of the day.
With the likes of Kelly Clarkson and Beyonce citing Mariah as an influence, there is no doubt the female population will preserve her legacy even if most males simply overlook her. Of course, JoJo is obviously influence by her. But even Britney Spears actually display some "agile melisma" in her first album.
In the hands of Mozart, the "unit" become the singer. Anyone who eventually listens to Mozart starts to realize that the orchestra/piano/violin starts sounding like singer. Thus, even in orchestral sections, they can display a flash of virtuosity with a "run", such as the opening duet of the Marriage of Figaro, where the opera singers don't do the runs, but the orchestra does.