Some games require more than just the files on disk, at least with older games, they set some properties in the registry or some such. How gog or heroic get around it I don’t know, but ah actual installer is guaranteed to give the same result every time.

For most people with stable internet and using the launcher this isn’t really an issue, but I imagine someone rural, on the ISS, part of the Atlantis expedition, or what have you, would enjoy to have a surefire way of getting their heroes 3 up and running

Not a use case for everyone, but for some it’s invaluable.