The problem is the intersection of people's intuition about closures from languages without mutable state bumping into the imperative world built of mutable state.

For example, equivalent code in Elixir:

    i = 0
    list = []
    list = list ++ [fn -> i end] 
    i = i + 1
    list = list ++ [fn -> i end]
    i = i + 1
    halfway = list
    list = list ++ [fn -> i end]
    i = i + 1
    list = list ++ [fn -> i end]
    IO.inspect Enum.map(halfway, fn f -> f.() end)
    IO.inspect Enum.map(list, fn f -> f.() end)

Would produce the functional-intuitive result of [0,1] [0,1,2,3]

Because there is no mutable state. Those repeated assignments to i and list are exactly equivalent to the scenario where each i was actually i1, i2, i3, etc.