Like I said, it really depends on what you are doing in the gym. From a general health standpoint, you shouldn't be putting more weight on the bar than you can reliably move around without injuring yourself. So if you are deadlifting and the weight is too heavy for you to reliably lift and then put back down (reliably doesn't mean dropping) then you aren't really doing a safe lift to begin with. The negative part of the deadlift continues working all the same muscle groups that were used to lift it, so it isn't good for hitting max numbers in the slightest. But if you can pick it up and put it down without dropping, you are effectively doubling the work you get from a single lift, and the secondary/support muscles get more attention. I know most people aren't dropping from their hips, and usually it's from the break point of the knee. And I've definitely dropped a few in my day, usually from overestimating how much I had left in the tank. I just feel from a general strength and health standpoint that you get more out of a complete up/down lift than simply going up for numbers.
Again though, I'm most definitely not advocating that people holding shitloads of weight up should try and play with it once they got it up. If you can't get it down gently, you still need to eventually get it down hah. But it definitely falls into my spectrum of unnecessary for healthy lifting for non-competitors. I feel the same about using straps, to be honest. If you are lifting for strength, then you should only pick up what you can hold on to. If you are lifting for numbers, then strap away. Otherwise you should improve your grip strength and increase reps instead of weight, until you can reliably hold onto heavier amounts. I do sets of 8 at 325, as I'm a little dude and not trying to power lift in the slightest.
Eidal: honestly, once you get to 250+ lbs, it is hard to set it down quietly no matter how big you are. The plates will start rattling regardless, even if you have bumpers on. But making the entire lift one complete smooth motion means that you are less likely to injure yourself since the muscles going up and going down are all getting work. It's more of specific lifting mentality than a hard fact. My opinion is that if you have to drop the weight, you weren't lifting something you could reliably control. Going for max weight by definition is lifting something you can't reliably control hah.