You enjoy the kool aid?
I am not saying that harmonic currents do not exist, all I am saying is the need for oversize neutrals is overblown.
In an otherwise well designed lighting circuit the loading on the neutral will not exceed its rating.
I have installed tons of oversize or doubled neutrals as we have done a lot of data center work. But it gets ridiculous when you look at the panel schedule and the circuit loading is only 4 or 5 amps for each 20 amp circuit and feeder loading a very small percentage of the load.
Have you personally seen damage of neutrals from harmonic currents?