Yes the writer had no idea of what a heavy caliber really is.
The .303 British has probably taken all game there is as has the 30-06. I agree with you that they are not first choice tho.
I have a good condition M1917 Enfield rifle in .30-06 Springfield that I inherited. It is not actually a Lee Enfield, which I have used as a teen to hunt deer and we referred to it as a .303 British.