I think you missed the point.

USING a SWR meter to tune a antenna does nothing to express resonance.

Dipoles by nature are a 1/2 wavelength or wavelengths in size.

The RG 8X was used as phasing lines - was the tuneable matching network.

Maybe what the person intended to say was that they tuned the antenna for a different frequency / hence at the frequency they desired to use, was a poor match with that antenna.

It stands to reason, if the antenna was not resonant, it would not receive as well at X Mhz.

In communications, we want to receive as much as we can possibly receive, unless what you are trying to do is local communications into the one local repeater - since most public service communications takes place on one frequency or one band of frequencies. Police, Fire, Ambulance etc...

When tropospheric ducting takes place, it is not uncommon to hear others communicating on your frequency, even if they are hundreds of miles away - even on 450 MHz...