I've heard this argument before but there are a couple of reasons why it isn't true. It would perhaps apply if the mobile device is stationary, if however you download a large file or stream music / video once it's begun it doesn't matter whether the receiving device moves out of its transmit range, it will still receive.
In terms of 5G over cellular, Max output power then is 30KW which is clearly massively higher than the communicating device can output, in addition there is nothing to stop a device transmitting on one frequency say 2.4GHz and receiving on another if its available. A smart phone is according to some claims capable of outputting 250mW on WiFi so shouldn't be a problem.
If it was the case that 1W was previously allowed outdoors that is going to be massively reduced:
"We proposed to make the band available for RLAN(including Wi-Fi)for indoor use with a maximum equivalent isotropically radiated power (EIRP) of 250mW, and outdoor use with a maximum EIRP of 25mW"