Debuggers allow to "look around" the running code. This is really helpful in large systems, where you don't necessarily even know all the components. It's fine

Debuggers allow to "look around" the running code. This is really helpful in large systems, where you don't necessarily even know all the components. It's fine when you're working in a nice segregated part of the system, where everything is well-defined. But it's not always the case. Also, single-stepping is a nice mental tool, kinda like rubber-ducking. You single-step and explain to yourself what is going on.