When you use a weight belt, you reduce risk while maintaining the rewards of heavy training. Using a weight belt isn't cheating, in fact weight belts are allowed during competition. It's smart to train with a weight belt because you can leverage the added stability into improvements in core development and overall strength.
When you use a weight belt, you are artificially reinforcing the muscles in your core. You wear a weight belt around the belly, above the hips, and you cinch it down tight. The structure of the belt solidifies your entire midsection into a unit, multiplying your core strength 10x! It is as if your abs have been infused with kevlar. The enhanced connection between all of the core muscles translates into feeling stronger and tighter.
Most people think the weight belt is synonymous with a back brace. It's not. It provides indirect lower back benefit by 360-degree support and contraction such that the lower back is less vulnerable to being isolated. The struggle most athletes have with lower back vulnerability is that those specific muscles have never been trained. Also, in order to function effectively, the lower back needs to move in coordination with the entire posterior chain, which is a skill that takes time and practice to learn.
You should use a weight belt (if you have one), when you approach weights that are in the upper ranges of your capacity. By doing so, you lower the risk but maintain the health and strength benefits. When you use a weight belt, you experience a level of core stability that you wouldn't be able to attain otherwise. When you then lift without a belt, you know what it feels like to have a core of steel and you can practice recreating that feeling.
It's beneficial to train with and without a belt though, and the belt isn't meant to cover up a technical weakness or mask an injury. Training without a belt means you can prioritize coordination, technique, and bracing. Training with the belt means you can apply more force to more weight, with less risk of injury, and reap the metabolic benefits thereafter.
The weight belt is only a tool. It's not smart to rely on the belt for feelings of safety or comfort. We should all prioritize moving with focus and control, and use the belt to leverage gains when it is called for in the program, or in competition!