Safe to use Wheel Adapters 5 on 4" to 4.5"?

I have no use for most pass car adapters. I can still remember a couple incidents back in the 70's. Guy comes in with what was a nice 65 stang. Rear quarter is all torn off it was a mess. Wheel adapter. Guy lost a tire at the strip. Wheel adapter (Not sure they are even allowed?) But it was there, anyhow.

How bad are adapters? Think about THIS. There are some fairly fast cars running stuff like the old Mustang 4 bolt pattern, or imports. So if a 5 bolt adapter came loose, it must be a weak sister.