1. He wasn't that good of a pianist or musician to begin with, just famous.
2. He also had a special piano that made it easy to play the way he played.
Ultimately, Horowitz had a bad technique, but he had enough skill and charisma to fool a lay audience.
You're either a troll or are clueless and should not be a senior member here. You've now lost the respect of every self respecting musician.
Horowitz was the concert pianist's Concert Pianist. And for good reason. Ask Martha A.
Anectodatally, I have found that, before I knew who he "was", I always gravitated toward his interpretations of most works. That sad O face you make when you finally "get" what the composer was trying to say through the fingers of a master came to mine almost every time.
That you are of the opinion that his was just a matter of charisma shows your ignorance. He had none. He sat stoically at the piano with expressionless face and expressionless body. None of the popular sways, graceful arm lifts, aloft wrist turns, emotional grimaces would you ever find in a Horowitz performance. Yet the dagger through your heart from the poetry he produces stabs every time.
But you wouldn't know anything about this.