One of the factors is that Apple forces shifts before the mainstream is ready. But they can get away with it because they’re Apple. This was the case before the iPhone BTW with floppy drive factors and the like. Once Apple blesses, others feel authorized to tag along.
Not saying the notch is the same thing but 3.5mm jack certainly is.
It's almost as if they can spot an emerging trend quite well (the move away from floppy disks, the ubiquity of USB and downloading software, music and video rather than buying physical media)
It’s not so much spotting trends. I’d argue all of those were obvious by the time Apple took definitive action. The difference is that most other vendors tend to leave in legacy connectors and media for the time period when pulling them out will lead to outrage in forums such as this one.
