How can it be more handy to type "false" than "0"?
Int allows you to take, let's say -1 and 2 as variable values too if you realise the basic on/off variable isn't enough at some part.
If (machine == -2) //off, broken and burning
{
...
}
is faster than
if (machineWorks && machineOff && machineBurns)
{
...
}