Citation needed. Cellular devices are an obvious application that needs dedicated spectrum allocation. Amateur bands (including volunteer civil defense helpers) and private terrestrial radio systems count on their spectrum being clean enough for use. Emergency responders have critical radio systems with dedicated frequencies. Ships and airplanes use dedicated spectrum allocations for navigation and reporting their positions, weather satellites have dedicated bands, safety equipment like avalanche beacons have dedicated frequencies, and so on.
None of this stuff would work if there were a free-for-all competition for whoever could shout the loudest on each band. To say that these bands are not important (or even critical to life safety) just because more data goes over unlicensed spectrum is frankly ignorant.