I get what you're saying and QT is obviously considered the "gold" standard in reefing.
My final thought is merely that one can spend an inordinate amount of time like you have, on setting up a proper QT and not enjoying your display tank. But even then, its almost likely that at some point there is human error, laziness, or frankly things you cant control that may introduce ich.
Having a family and kids are one of those main things we cant control. Also, id be willing to say that doing a QT is also playing russian roulette. You're betting that youll never cut a corner for yrs, youre betting that putting 5 tangs in a tub for months wont stress them to death.
Sorry. Not trying to argue anything its just such an intriguing concept with such vast opinions.