I have a 5X - purchased an 8 and waiting on it. In my experience, they're the only company so far that automatically stores the WhatsApp media to the SD card without any user intervention. Just does it automatically. On each official OS I've tried so far. I tried some custom ROMs but they basically forced me back to stock with the absence of that feature.
With the 8 and more storage space I probably won't need it - but the price plus quality of the device will keep me with the company for a long time.
Knowing the solution doesn't mean knowing the method. Yet answering correctly and regurgitation are considered "learning" and "knowledge".