It seems both (HLS and MPEG-DASH) use the same the Media Source Extension API. So why does HLS video only work on IOS. Why doesn't MPEG-DASH work on IOS? What is the core difference making this "http://nickdesaulniers.github.io/netfix/demo/bufferAll.html" video not work on IOS? Where is the problem? Is it the new MediaSource, .addSourceBuffer, .appendBuffer, .endOfStream() or .mp4 file.
Only apple can answer that, and so far they have not commented.
EDIT: iPadOS 13 will/does support MSE. iOS 14.5 (iPhone) still doesn't not.