Serious Reburbish question

I'm hoping this is the proper place to post this:

I’m relatively new to military weapons collections, but have been a gun lover for over 40 years. I have collected weapons such as K98, M24, M48, Enfield Carbine, Enfield NO.4 MK1, Nagant M38 to mention a few. I also have some revolvers and pistols dating as far back as 1850. I have a question that has long bothered me about the collection of these and other fine rifles, revolvers, pistols etc.

My understanding is that upon obtaining these weapons, one should never refurbish, or restore either barrel (or metal) and stock as this causes the value to go down and be less attractive for collectors.

My question is, why is this so? If I buy a rifle, k98 for example that has rust on the barrel or other parts, isn’t it for the benefit of the longevity of the rifle that I re-blue for example? Isn’t it better to stop the rust before it has a chance to eat the metal more? Seems to me if someone has my k98 (one that was reconditioned and rust removed) hundreds of years from now, it would be in much better shape, and firing condition, and higher in value, and demand than had I not done so. Or if the stock has serial numbers or WaffenAmpts stamped into it and one can make them more legible and more lasting by stripping, re-staining, and re-sealing the wood? How would that not do more to preserve the weapon? I’ve never read where it suggested refurbishing instead of letting it continue to rust.

I am only posing this question to get a further education in this matter for future reference. If it sounds like a smart ass question, it is not. I’m trusting that there are many out there that can logically explain and enlighten. Its confusing for me.

Thanks