The high frequencies are one of the techniques in 5G that enable faster data transmission. Another is beamforming: instead of broadcasting data in all directions, it is only sent in the direction of your smartphone. The thing is, there's no change for the receiving smartphone (same RF transmission power), just reduction in interference for others.

[edit: thereby, you can have more devices talking on the same frequency without disturbing each other, since they are separated by the "beams"]