Except that you have to either indent with only tabs or indent with only spaces. Any time you mix tabs and spaces you are just asking for disaster.

If you indent with only tabs you can’t align things except on tab boundaries. If you have a function that takes 10 parameters and want to do it on multiple lines, the alignment of the extra parameters is going to be ugly.

If you indent with only spaces, you can indent things so that all the parameters line up directly underneath the parenthesis, for example.