I dunno, my buddy who just got a degree in high energy plasma physics working on fusion reactors might disagree with you.
And really, you just sound like every crank ever who thought X technology was totally unfeasible and always would be -- until it wasn't. So currently attempts haven't found a solution to the reaction vessel destruction problem. That does not mean someone in the future couldn't figure that one out.
It's not false. But it's also not a universal constant like the speed of light or something, absent a reason why it couldn't be planned for and dealt with, I'm inclined to treat it as an as-yet-unsolved engineering challenge.
Neutron radiation, plus the unfortunate geometric fact that the surface area/volume ratio of a fusion reactor will be low, compared to the fuel rod surface area/volume ratio in a fission reactor.
What this does is ensure that even operating right at the limits of neutron damage to the wall materials, the volumetric power density of a DT fusion reactor will suck. And that will destroy the economics.
Research into vessel liners is ongoing and promising. 7-X is getting carbon-carbon, JET has an upgrade going in about now. It's a materials-engineering challenge, but not a showstopper.
And really, you just sound like every crank ever who thought X technology was totally unfeasible and always would be -- until it wasn't. So currently attempts haven't found a solution to the reaction vessel destruction problem. That does not mean someone in the future couldn't figure that one out.