Just like with cars, any computer or laptop would benefit from maintenance at least once a year. If you have a dusty environment, you might require maintenance to be performed even more often.

Dust is the main issue, it blocks the airways inside the computer or a laptop and causes overheating, which in result over time puts more pressure on the motherboard, CPU, Graphics card and it would then fail a lot sooner than expected. Also, the thermal compound/thermal pads would dry up over the period causing severe overheating to your GPU/CPU.

You can look at it as driving a car with an overheating engine or at HIGH RPM at all times, the difference here is that the car’s engine would fail a lot faster, the CPU has integrated safety overheating mechanisms which put it to a safe mode automatically by drastically reducing it’s speed (thus slow performance), however the motherboard and the power supplies have no such protection, also long term high temperature exposure to the CPU and GPU would cause the damage, even though it doesn’t destroy them in a short term. In Other words, the lack of maintenance is overheating, which significantly reduces the lifespan of your device.