Belts are the first thing that come to mind, but really there’s lots of similar accessories that do the same thing. Belts, knee sleeves, wrist wraps, lifting shoes; things that try and give an extra edge to help in lifting more weight. They do a really good job of giving help too, but are they necessary, or beneficial, and should you look into using them?
Like most things there’s a time and place to throw on a belt or other piece of assistance, and it depends on the person how big of a difference it makes. The big benefit of weightlifting shoes is the elevated heel making it easier to get into a deeper or more upright squat position by taking out some of the ankle flexion, but if someone has mobile ankles already they aren’t gonna notice as much of a change. Wearing weightlifting shoes isn’t a terrible idea because really it’s trying to help you get into a better position, but they’re heavy and not made to move around in a lot, making them terrible for metcons that have anything other then a barbell in them. Using them during your barbell focused stuff is fine, but working towards achieving the same positions in your regular workout shoes is just going to be more universal since it’s not very common for us to just be doing heavy barbell stuff.
Items like belts, wrist wraps, and knee sleeves are a little different than shoes in that they’re purpose is to give outside support to the body. When I say support I don’t mean help either, I mean literal compression and support to joints. These I have more of an issue with because they very commonly become a crutch for people. Before a barbell is even gotten out or loaded up I’ll see people pulling their knee sleeves up or tightening up their belt. My general rule for accessories like this is trying to not use them till past 85% loading, otherwise what is your body for! I’ve got a feeling that you’re not walking around your house with your knee sleeves pulled up for when you have to get up off the couch or toilet, or with your belt ready to go for when your kid wants you to pick them up or you drop something off the floor and have to pick it up. So why are you counting on those things right when you get in the gym?
The common reasoning here is because people don’t want to get hurt, or because something already hurts when they aren’t using them. Maybe the focus should be on getting your body to the point where doing stuff without assistance doesn’t hurt, rather than trying to measure how strong your accessories are. At the end of the day exercise is either a stress reliever or a way of making common daily life easier, or both, so it shouldn’t be something that is cause us greater stress or harming our bodies making daily life harder.