Fact or Fiction--Trailer tie downs

I'm with muddog,
I have moved cars across country for 30+ years. I always tie down the lower A frame, and the rear axles. I let the suspension do what it was meant to do. I found early on if you tie the car down on the suspension, eventually that car will pull on the straps, eventually loosening them up. When I used chains, the constant bounce weakened the tie downs,and the car being rigid beat up the trailer, very dangerous when going through the Rockies. A 4000 LB car tied rigid to a 2,000 LB trailer becomes 6,000+ on the four trailer tires 100% of the time. Tied to the frame I then have two sets of suspension working, Instead of just the trailer springs. Short distances would be ok, but across country it is different. My experience has been only single 20ft - 28ft trailers, not the big haulers, they may do things differently