As I understand it the issue is thus:
Type A to C cables:
At the Type A end, there should be a certain resistor (56Ω) between 2 points within the plug to stop the phone drawing too much power (3A) than the plug/hub can provide. In theory this could damage whatever the A end is plugged into, but not the phone at the C end.
The cables that don't meet this spec can cause the phone to request 3A from the socket, whereas the correct cables should detect what the socket can provide. Or something along those lines...
Type C to C cables:
These should be 'safer', in as far as they shouldn't bork the USB plug/hub end - but poor cables seem to charge at a much lower rate.
MicroUSB to Type C Adapters:
As above, these seem to be safe but will not work for some devices (Chromebook Pixel 2), but should charge Type C phones ok - albeit at a max of 2.4A.