Could someone please explain what on earth use this would be to anyone with a light single strapped to their arse?
VOR reception is limited by the same thing. On a long, x-country flight at relatively low level (and without a GPS), it helps a lot to have a rough idea on when VOR reception can be expected.
But it's totally irrelevant for VHF communications because VHF stations all have a Designated Operational Coverage (or whatever the name is). Usually expressed as a maximum altitude & maximum distance to station. If you are within this DOC you should have good VHF reception (except if there are terrain issues like IO540 mentioned) and if you transmit outside the DOC, you might be interfering with the DOC of another station which happens to have the same frequency.