The confusion arises from the fact that, when referring to RAM, we (mistakenly) use 'kilobyte', 'megabyte' or 'gigabyte' to mean 2^10, 2^20 or 2^30 bytes. The replacement terms of 'kibibyte', 'mebibyte' etc. do not appear to have gained widespread adoption. One can nostalgically appeal to the good old days in which a megabyte was a megabyte, and screw the Bureau International des Poids et Mesures, but those days are long gone.

However, in common usage we now have the pretty awful scenario where, if a person says "a megabyte", the actual number of bytes they're talking about can change depending on where the data is stored! A megabyte of RAM is not a megabyte of hard disk space. The solution would be to standardise on binary prefixes, since we pretty much have to talk about RAM that way, and a consistent measurement across different media is eminently sensible.

The "hard drive maker conspiracy" story is driven by the fact that manufacturers have no real incentive to switch to binary prefixes, because that would make their drives look "smaller". Do you want the 300 gigabyte drive or the 279.4 gibibyte drive? Aside from the fact that hardly anyone knows that a gibibyte is, in the absence of any more information the larger number is probably better. Even worse, if you created a 300 gibibyte drive to compete with the 300 gigabyte drive, consumers would probably not realise that the 300 gibibyte drive is bigger. It's not exactly a conspiracy, but it is a suboptimal arrangement that results from the manufacturers' incentives.