It wasn't my thread, but I agree with you 100%. If any multimeter shows anything like what the voltage SHOULD read (surely anyone with the slightest bit of electronic knowledge, ought to be able to work out a ball park figure - but perhaps not, as common sense, isn't that common!), then it is a pretty good tool to use.
It could be 10% out, up or down, but it's totally irrelevant as long as it's consistent. For the intended purpose, a guide is good enough.
This thread has to be one of the most 'realms of fantasy' threads on RMWeb and let's not go to the hinted at insults - whoops just did!