Not exactly by design, but it was available as an OEM part and enough people had dropped phones for there to be YouTube vids. I don't know about mad skillz. It's comparable to working on a laptop which I've done a bit replacing batteries, fans, drives etc.

If you're thinking about doing it, then a search in your search-engine of choice should reveal whether the part is available and whether there are instructional vids. If you can find both then it probably isn't that hard to do. The hardest part with the OnePlus 1 was being organised and brave, because it meant dismantling almost every part of the phone.