Example: a toaster shouldn't need a big powerful MCU. 8-bit MCU should be plenty. And you're not going to toast a piece of bread for more than 50 days. Maybe 50 seconds max. And if you're mass producing toasters, saving a few cents per MCU by choosing one with less flash and RAM will save a lot of money. So in this case the developer may decide that time_t should be reduced because it makes sense.
Remember that the range of time_t has to support the epoch as the minimum (zero) value. Now is the running time plus the epoch (CLOCK_REALTIME).
