Friction anti-sway device use in rain or wet roads

You are way over thinking this. Your quotes are correct - sway control adds a safety factor and provides a level of control. No one is disagreeing with that. Use sway control when appropriate (which is the vast majority of the time), get used to towing your trailer, and you will be fine.

Then you will come back here in the future and give your own opinions on sway control to new owners...