I was in an accident a year or so ago while pulling a trailer with an ATV strapped on it. Now this ATV weighs at most 700lbs, and was strapped in using 2" 10k lbs straps at all 4 corners, which at the time I thought was overkill. I was in traffic and almost at a stop when the trailer was rearended, how the guy missed my big blue F350 with a 15 ft trailer behind it stoped in traffic is still beyond me, but, both of the straps in the back corners were torn in half and the ATV moved almost all the way to the front of the trailer.
I totally agree with being prepared for the worst on the road because you never know when (not if) that idiot will cross your path. I would much rather deal with the slight pain in the butt at first then the miserable headaches after the fact for being lazy (or not careful). Straps have their place and chains have theirs, and while nothing can guarantee that chains won't break either, use chains for a load as heavy as a tractor.