Smartphone enclosures themselves are usually quite simple, and if you look closely, you will see that most small devices are designed much more simply than Apple products. Apple dedicates more effort into modeling plastic flows, shrinkage, and other manufacturing issues than most other OEMs. Apple also dedicates more effort to refining production techniques than most other manufacturers. Companies like Samsung and HTC have volumes almost as large as Apple's, and are not far off.
Molding parts has gotten a little easier over the last 10 years. Molding machines are more easily tuned, and CFD tools have gotten much better and easier to use. The Bolt post is addressing new companies with 1k-100k/yr volumes and less expertise than Apple, and the post is largely correct.
After reading further comments I decided to compare all of the white plastic devices I have, and they're all a often noticeably different colour, even on different parts of the same device.
Molding parts has gotten a little easier over the last 10 years. Molding machines are more easily tuned, and CFD tools have gotten much better and easier to use. The Bolt post is addressing new companies with 1k-100k/yr volumes and less expertise than Apple, and the post is largely correct.