Exactly, it was solved by using small cells to share the spectrum geographically and with higher frequencies that had the double benefit of permitting more chan

Exactly, it was solved by using small cells to share the spectrum geographically and with higher frequencies that had the double benefit of permitting more channels inside a band and smaller equipments. Using frequencies higher than 100 MHz meant costly hardware in the sixties/seventies. And short antenna on a portable device were frankly ineffective at 100 MHz, they had to be long: A quarter wavelength at 100 MHz is around 80cm/2.3feets long!