True. In some ways conservation is almost like archaeology! Especially in the example you gave. I remember seeing a piece on the restoration of Holbein's "The Ambassadors", a 15-16th c. oil on wood work at the National Gallery in London.
The piece had faded, cracked, warped, and simply just started to go south. The wood it was painted on is not a single piece but planks held together. So they had umpteen sections all deciding to go their own way. The paint was just messed up by sun, heat, humidity, etc.
Over, I think, two or three years they went over the whole thing with cotton swabs, 3 bristle brushes, and magnifying glasses to fix it. Just like an archeologist slowly brushing away at the detritus of eons or having to piece together thousands of tiny shards.
With that in mind, I understand why so many collections are paranoid (rightly so) about too much wear and tear on their pieces. It is much cheaper to keep something in the dark than to fix it later.