Why can't we just make all wireless networks use integer multiples of base frequency?
It's not that easy to distinguish different frequencies when they are close to each other so you'll need to make sure that there is sufficient spacing between the frequencies. Also, you can't just keep transmitting higher and higher frequencies. At some point there will be a limit of the highest frequency that can go through a wire or whatever transmission mechanism you are using and also the fastest computer that you have to process it. So once you cap the highest allowed frequency your method comes down to dividing up the remaining space among a finite set of frequencies. In other words, you are proposing to allot a uniform bandwidth to each of your channels, which is exactly what you said you were trying to avoid.