Had a client recently ask me if he could use straps for his snatch grip deadlifts. I said absolutely as that is an exercise in which I wouldn't want the load to be inhibited simply from a grip standpoint (since a snatch/wide grip can be difficult to hold on to.)
In the past, I had a client doing a barbell row with one under/one overhand grip, stating that the bar was getting difficult to hold on to for their bentover rows.
The point of using straps is to be able to hold on to the weight while still using a double over hand. Some would argue, "Well, if you can't hold on to it, then you shouldn't lift it." Those are usually the trolls who have nothing better to argue about.
If we really look at why straps are being used, it's either because A) it's an exercise that is difficult for the person to hold on to (like a snatch grip) or B) it's an exercise in which the person wants to maintain a double overhand grip.
Anytime a person switches to a mixed grip, the shoulders become asymmetrical which can put stress on the lower back. It doesn't seem like it would, but by simply supinating one hand to an underhand position, that enough can cause a twist or a helicopter of the bar. Even if you lift the bar "straight", the body still has to compensate for the asymmetrical grip. Many powerlifters will have one erector that is slighter larger than the other for this reason.
There is a time and place to use straps. If you are doing back work like stiff leg deads, RDL's and other exercises where the weight of the bar is not important, then use straps. It will be less torque on your back and keep you in a solid and straight position.
If you planning to compete in powerlifting, then I would NOT use them for regular deadlifts, only because you need to be able to deadlift without them in a meet.
Bodybuilders, who are not competing in powerlifting, often use straps for their deadlifts. Again, for them, they aren't concerned about holding on to the bar. They don't want to bothered with their grip when the focus is on their back work.
Using straps is not inherently bad or wrong or dumb. In fact, I often encourage it for accessories in order to keep the low back in a more symmetrical position. Competition work - stick to your normal strapless grip.