Weird. Digital recording and mastering was definitely a thing at that time. You’d think they would have been crashing the HDDs of PCs in the recording studios.

Not weird at all. This problem manifested only with some model of 5400RPM laptop hard drive (2.5"), but a recording studio would likely have been using 7200RPM 3.5" desktop drives. Different resonant frequencies, more sturdy mounting, more distance between the speakers and the hard drives.

Apparently pro tools came out in 1989, makes me think this may or may not be true. This article has some info about the mixture of analog and digital tools use to record:

> The main event was a brand-new mixing console called the Harrison Series 10, which was the first analog console to feature a digital control surface, with full automation of all parameters. Jimmy Jam and Terry Lewis were the first studio to have it, according to Jam. This meant that they could cut down the time it took to switch songs to about 10 minutes because complex mixes now required little-to-no cross-patching.

https://reverb.com/news/the-making-of-janet-jacksons-rhythm-...

They probably didn't use laptops in which the disk and the speaker are next to each other.