If I thought that one in a thousand times, a collection cut might have concentrated something that could be lethal, I would still advise it and do it myself when somebody bottoms out nutrients and needs to add some back in a pinch.
I'm unsure why it has to be pushed into anything other than a conversation.
Because, in my own firsthand experience, an otherwise healthy tank suddenly experienced a die off that cannot equate to a simple loss of a sick or injured fish. I literally lost half of the fish in this system within a week. NO changes were made, NO fish added, No change in feeding schedule or ammount. NOTHING. The ONLY thing was the overflow of the skimmer. And to add to that, once I cleaned the skimmer, not only have I not lost another fish, but the ones who looked sick are better and the new fish I added since are happy and healthy.
Understand this.. This is a 180G system with a 50g sump. No corals and healthy predatory fish. These fish are the least demanding of high water quality around. Clown trigger, flame angel, powder brown tang, domino damsels and 3 stripe damsels.