Chalo
100 TW
That's not true. No matter how stiff the rim, it flexes some amount. A 2.7mm spoke has 2.25X the cross-sectional area of a 1.8mm spoke, so it will slacken at 44% of the load required to slacken the thinner spoke, given the same spoke tension. A stiffer rim increases the required force to reach that threshold, but it's still 44% of whatever it takes to slacken the thinner spoke.You keep on bringing up thick spokes slackening under load.....but this only happens when using rims with poor radial stiffness.
Why don't you put on a couple hundred extra pounds of body weight and build a few thousand wheels, then get back to us with what you've learned? I think you'll figure out what I have learned.