The only way there should be significant nodes and antinodes along a transmission line is if the load match is (very) bad. Not sure why this phenomenon would ever happen in the real world, unless there's a mismatch problem.
This is basically the definition of VSWR. No mismatch = no standing waves. If you're seeing a pattern of degradation due to uneven heating in a piece of coax, check the antenna.
If the coax is operated at max power handling capability with a good match, then it wouldn't take much reflection (anywhere in the system) to cause internal arcs or heating. No real component has an infinitely low reflection coefficient.
This is basically the definition of VSWR. No mismatch = no standing waves. If you're seeing a pattern of degradation due to uneven heating in a piece of coax, check the antenna.