Years ago I sent a listing to Tuck Publishing and asked if they could fill in any blank spots. Fires also wipe out a company's records and files as does relocation. Then, there are companies that couldn't care less, and are very nonchalant about their history. Sometimes they wake up and begin to reconstruct, while others never do. One company actually was offered an entire collection accumulated over 45 years of working for the company.
Many companies just throw out and burn stuff, including original artwork and all the documentation.
The world can be grateful to pack rats, collectors, hoarders, rescuers, and those with a propensity for ensuring that some history will be salvaged, so you and I and later generations will know just a bit more about the items we collect and deal in today.