I still think the difference to me as a programmer is largely semantic (except when the performance has to be considered): "rebinding" or "in-place mutation", in both cases it is a mutable variable to me.
with rebinding:
def thing() do
x = 10
do_something(x)
# x is 10, non negotiably, it is never not 10
end
def thing() do
x = 10
do_something(x)
# who knows what x is? Could be anything.
end
Thanks!