I still prefer to indent C with tabs, and I'm not the only one. It's really not hard to handle tabs well, as a code editor or as a programmer. You can view them as whatever width you like. You can have marked to distinguish from spaces (e.g. vim's "set list"). They've been around for longer than you have so there's no good excuse for forgetting about them.
But you'd be wasting holes.
I just felt the comment was suiting since it must have been about when they were still used that you couldn't automate indentation.
I think the column 6 rule and line continuations were removed for FORTRAN 95.
Try using tabs to indent e.g. arguments to function one under another, and weep.
Where the terms are distinguished in a programming context, that's alignment, not indentation; tabs for indentation, spaces for alignment is a common suggestion.
I despise that formatting, and use: