When the car was stripped, two of us could lift it from the front.
What am I missing here ? What rigging ? It would be a lot more weight lifiting the motor/trans combo out of the car than lifitng the emptied body shell over it. No, it didn't just work. It works great, and is about as safe as it needs to be, with people being 4-5 feet away from the car at that time.
I'm sure all you say is true. Your combined experience is not being debated. The problem arises when some newbie remembers your method and attempts to repeat the same and the car is not stripped, he uses lighter rigging and/or inferior fasteners along with possibly exceeding the capacity of the hoist with the boom fully extended.
While it may appear no different upon visual inspection to the untrained eye, if one were to use an imported hook, low grade bolts, and/or a low grade chain not approved for overhead lifting, they could be setting one hell of a mouse trap.
The strain on the chain used across the front bumper mounts is just one consideration. At the oblique angle as used, the load is magnified greatly on the chain. As an example, if the safe working load of the chain were 2,000 lbs, the imposed load limit as used could be reduced to 500 lbs or less! Still sounds safe? Remember shock loads may be up to 8 times the actual load. One alternative would be to use a spreader bar setup and keep the chain rigging vertical or at least close to vertical.
The bolts used to fasten the chain is another consideration. I would hope one uses grade 8 fasteners for lifting applications. They have a proof load of 120,000 psi as compared to a cheap grade 2 bolt which may have a proof load as low as 33,000 psi, or only one fourth the capacity. Many people mistakenly think stainless steel fasteners are high grade when in fact they can be rated as low as 40,000 psi or one third the capacity of a grade 8 fastener.
The chain selection is another important factor. Take for example a common 1/4" welded link chain. It may come in grade 30 which has a safe working load of 1,040 lbs whereas it looks identical to grade 40 which is rated for 2,600 lbs. But neither is approved for overhead lifting applications. The lightest approved hoisting chain is 9/32" with a working load limit of 3,500 lbs.
I apologize for sounding like I'm preaching but I just want to make sure safety comes first. Any hoisting should always be approached with caution.