This has nothing to do with marketing, although the Base10 used by disk manufacturers is (Base10 seems bigger than Base2 and that is good for sales).
Granted, you are not old enough to remember, but early computers did everything in Base2, and it was all called kB, MB, etc. Only recently (1998), some dipstick felt it was confusing to use kB etc for a Base2 system and introduced KiB, MiB, etc.
Computers are binary and hence use Base2. As a result, kilo means 1024. If simple people can't get that, that's really their problem. Base10 on computers is to satisfy the ignorant and the stupid masses.