I didn't write it's impossible to make portable CD players, I too owned one with similar buffer size, just that they make little sense nowadays, with the reasons being the following:

• mechanical parts that have to move with high precision
• limited amount of music per medium (typically up to 80 minutes)
• lack of metadata apart from CD-TEXT which isn't universally supported
• flat structure only (tracks 1-99, not a real problem with the limited amount of space)
• not the greatest battery efficiency

All these limitations lead to portable CD players vanishing from shelves because portable MP3 beat them in all of the above over 20 years ago. Today, you can just use your phone , which most people have with them most of the time, and if you're using a lossless format, you're not losing a single feature.