In my opinion, a key thing for some MBAs is to get away from narcissism, from the defensive fantasy of their own perfection. At top business schools, I come across this attitude a lot with applicants or students. People refuse to admit that their soft skills are weak. But, at the same time, imagine the impact of an elective on negotiation skills. Everyone feels and admits a huge benefit from that, and it shifts not just the skills but in a way one's whole attitude towards cooperation. That's one simple example of how education can shift a soft skill a lot. Another clear example is cross-cultural working culture: a small experience can lead to a big difference.
So, no, face-to-face work isn't magic. No-one said it was. But can be really helpful for people whose existing role does not allow them to develop their soft skills, and who otherwise might not be aware of their potential to develop.