There are many good and honest people who sincerely believe that any lubricant on the cartridge or in the chamber produces an extremely hazardous condition. Others, equally honest and sincere, feel that no rational gun designer/manufacturer would create a military rifle that self-destructs when fired in a condition that is certainly common in service, where lubricants (including water) are frequently present on ammunition or in chambers.
My own experiences in handloading for various Lee-Enfields over a period of 50+ years tell me that the hazards are exaggerated and .303 case life can be significantly extended with a small quantity of lube - judiciously-applied, causing no measurable damage to a Lee-Enfield in good condition if normal sound handloading practices are followed. I have not made any comparative accuracy tests, lubed vs. dry, and therefore make no assertions on that subject. It seems a useful area for investigation by someone with the necessary resources, including an open mind and a good measure of curiosity.
Many individuals are more inclined to caution than to risk. This is a personality trait useful for survival in some situations - but may inhibit expansion of knowledge in other circumstances. It seems to me that many internet gun enthusiasts are the cautious types and enjoy posting dire warnings about practices they haven't investigated by any means other than reading selected publications. This is not a bad approach, per se, but does run the risk of stifling practical investigation and possible advancement of technique.
Believe nothing, no matter where you read it, or who said it - even if I have said it - unless it agrees with your own reason and your own common sense. - The Buddha