It's not just money. Some companies did DVD linux ports 10-15 years ago which haven't been installable in years. The linux environment isn't as stable as windows.
There are Linux releases on GOG which are not playable on a modern distribution without heroics. Too much churn in system libraries/dependencies/whatever.
The only way to ensure I have a working backup of a GOG installer is to download the Windows release even when Linux is an option.
