Why? 60GHz is heavily attenuated by just about everything. If it's in room, you'll get decent coverage either through directly through LOS, or slightly attenuated by multipath. But it won't go through the walls too well, and it gets attenuated pretty quickly even by the atmosphere.
Check out this. https://transition.fcc.gov/bur...
But isn't this bad? Well, if you are hoping to drop a single 802.11ad access point in a building, and hoping to get whole office coverage.
But, if your 802.11 in the 2.4GHz and 5GHz spectrum are saturated, you can drop an 802.11ad AP into conference rooms, or places people use a ton of bandwidth, and offload it. Oh, and one more thing. Pretty much every implementation of 802.11ad that I've seen makes heavy use of either an array of highly directional antennas or beamforming. This just helps out more with spectrum re-use, and non-interference between different 802.11ad devices in proximity.