Power leaves the panel and travels through branch wiring inside your walls, ceilings, and floors to reach every outlet, switch, light, and appliance in the home. You never see it, but it's the path everything depends on, and it's carrying loads today that it may never have been built to handle.
Modern wiring does two jobs at once. It delivers power where you need it, and through grounding and protection it gives a fault a safe path to ground instead of through you or into the framing.
When that wiring ages out, it doesn't stop working all at once. It just stops protecting. Insulation breaks down, connections loosen, and the safety margin the home was built with quietly disappears behind the drywall.