It’s not about the absolute number on the bar - it’s the relative intensity/percentage of current maximal potential for exertion. This means a guy who squats 225 as a max needs to be doing this with everything over about 135 probably if he wants to stay as safe as possible. It’s also not about “not breathing” - it’s about creating ideal intraabdominal pressure.
So things like benching or seated pressing this is less necessary, and certainly not isolations or most machine work, while things where the core is constantly loaded like bentover rowing, all deadlift variations, good mornings, cleans, standing pressing/jerks it becomes imperative. You have to breathe between the reps, not during the eccentric or concentric.
How many guys do you see at every commercial gym wearing a belt the entire arm session who will tell you how barbell rows or deadlifts took their back out? Plenty, and it’s not because they were uniquely fragile - it’s because they just didn’t know how to brace properly.