I was nosing around the root directory when I found a file called "verity key". I copied it to my SDcard and looked up what it was and apparently since Android 6.0, there is a "feature" called verity which can detect any modifications to the system partitions when the phone boots or when the partitions are accessed. Some phones still boot and give you a warning and some refuse to boot all-together.
I really hope KingRoot finds a way to disable verity. I know little about it but I already know enough not to like it.
TL;DR
Any non-temporal root could easily brick the phone.