The filament path does degrade. You want your filament to travel through your PTFE tube and nozzle with the smallest air gap possible (from extruder to nozzle- filament roll to extruder doesnt matter as much).

Due to wear over time, your PTFE tube and nozzle are both “wear items” like the brakes on your car.

Here’s a great article with photos of some new and used nozzles that have been cut in half to show the wear.