Modifying a list iterator in Python not allowed?

Simple example:

myList = [1, 2, 3, 4, 5]
for obj in myList:
  obj += 1
print myList

prints

[1, 2, 3, 4, 5]
[1, 2, 3, 4, 5]

while:

myList = [1, 2, 3, 4, 5]
for index in range(0,len(myList)):
  myList[index] += 1
print myList

prints

[1, 2, 3, 4, 5]
[2, 3, 4, 5, 6]

Conclusion:

1. Lists can be modified in place using global list access Lists can
2. List items can NOT be modified in place using the iterator object

All example code I can find uses the global list accessors to modify the list inplace. Is it so evil to modify a list iterator?