The article you read has either been misinterpreted or was monstrously misleading. It is possible that what they were referring to was the fact that the frequency response required from an analogue medium was only enough to record 100kB/s of digital information. That does not mean that the recording quality of the original recording was equivalent to a digital recording of that bandwidth. Such a conclusion is entirely incorrect.
The Beatles were originally recorded using analogue tape technology. The frequency response of the analogue tape machinery that was used is entirely independent of any digital sampling bitrate that might be used in the future to encode such a recording.
Recordings done way before the Beatles were performing still stand up to scrutiny today as extremely high-quality recordings.
You should be sure to understand the difference between analogue and digital recording techniques. With analogue, the microphone, preamp, recording media and reproduction circuit are all significant contributors to the signal path. With digital audio everything between the Analogue to Digital Converters and the Digital to Analogue Converters is simply a matter of data storage and transmission.