Just because a product went defunct does not mean the entire code base is obsolete to the company.
Suppose I release software that makes a profit for a while, then falls off and starts costing me money, obviously time to retire that thing. However, a ton of code in that original product was a stepping stone for newer projects. I now have two choices.
A) Drop support and give world+dog my code, giving everyone a look into my existing products.
B) Keep losing money on the old project and make up for it by overcharging for my latest work.