Antifreeze serves two purposes, The first to stop the engine from freezing and failing,
The second purpose is it is used as a rust inhibitor.
Without antifreeze as an inhibitor rusting on the metal components would cause a problem, While the aluminium components would slowly be dissolved.
The deposits of this would settle in the radiator matrix clogging the radiator and heater.
For this reason Modern cars have Antifreeze change written into there service schedules.
Most vehicle manufacturer recommend between 3 and 5 years, the cost of replacement is very little from £35 -£80.