I used to explain to non-technical folk (real people) that the reason ADSL is distance limited is essentially the same reason that you can only hear the bass beat and not the violins and soprano of a noisy neighbours music (very middle class neighbours with thin walls).
Higher frequencies attenuate quicker than lower frequencies, so the drums passes through walls when the violin frequencies are more quickly absorbed.
ADSL uses the frequencies we can’t hear because we want to continue to use the phone line to speak to each other. The lower frequencies needed to carry phone calls travel a long way down a copper wire, but the much higher frequencies used to carry a broadband signal will attenuate more quickly just like the soprano living next door.
As we demand ever higher bandwidth, we need to use more and higher frequencies which will fade away even more quickly, which is why the broadband equipment in VDSL, like BT’s Infinity service, needs to be closer to our homes.