It's been clear as day for 25+ years how to properly quarantine and treat a fish such that it won't bring pathogens into the display tank. This isn't the cutting edge of husbandry. People just want to stick fish straight in the tank and not deal with the process, and then end up half assing measures when stuff goes sideways.
If thats so - why is there such discussion? In fact, IMHO you are incorrect - it is 'cutting edge'. 25 years ago there weren't the same products available as there are now, so its always 'cutting edge'. Even the knowledge of parasites has changed in 25 years. I dont see anyone suggesting sticking fish in their tank in this thread - so whats the point.