There is no particular reason, that part is certainly cultural. There aren't even seven, they are twelve equal slices, called semitones. There are infinite slices an octave can be divided into, we just picked one kind of division completely arbitrarly ~2000 years ago because we needed to build organs that sound good together and those people then thought those divisions were enough to express all kinds of emotions. Of course that process took a long time to finalize to what we call now western music.

The ear doesn't care too much about which frequencies, but that they are the same ones. That said, an octave is the doubling or halving of those frequencies which we identify as them being the same note. So, I find it very hard to believe what the article is claiming, also because one reason we can listen to music in low quality speakers is that our brain fills in the missing fundamental[0] so the doubling/halving part seems to be integral to our perception. I don't see how such a psychoacoustic effect be trained or be culturally based.

But on the other hand, tuning into a particular division is very hard to get rid of, westerners can't hear scales that have more than 12 semitones, arabic, indian and eastern music in general is like that and to a westerner ear these sound mostly dissonant and you need to spend a lot of time listening to start appreciating the expression.

[0]: https://en.wikipedia.org/wiki/Missing_fundamental