I am not trying to be contrary either.
But...
What you are saying does not match with my interpretation of the Federal Standards (see previous post). 1) You CAN use the sum of the individual tie downs to derive an aggregate WLL. In fact, you are
required to do so.
2) There is
nothing in the standard that says you cannot use straps for a small tractor as described by the OP. The standards for heavy equipment (>10,000 lbs) are a little different, but for small tractors there is no such prohibition against synthetic webbing.
Safe and legal does not necessarily mean everyone has to use chains on every load.
Anecdotes and conjecture are no substitute for first-hand knowledge of the local, state, and federal laws.