Dust is an insulator. As it builds inside vents and heatsinks, heat stays in the machine, fans spin harder, and components throttle or wear faster. Regular cleaning is genuine maintenance, not cosmetics.
Technique matters. Compressed air blown into a fan can spin it beyond its design speed and damage the bearing, so fans should be held still while cleaning.
Screens and coatings are delicate. Household glass cleaners strip anti-glare and oleophobic coatings; a barely damp microfibre cloth is safer and just as effective.
Ports collect lint that prevents cables from seating fully — one of the most common causes of intermittent charging, and one of the easiest to fix.