Comment alignment can matter (Score 1) 479
I wonder how long you have been writing code, if you don't yet realize that sometimes aligning things vertically across several lines can increase clarity. If everybody gets to set their own indentation amounts (by changing tab width), then this benefit is lost. Tables were invented for a reason, and sometimes code is tabular. And if you think a tab character is how you get a table, you are sadly mistaken.
For example, having same-line comments start at column 60 (when possible) makes code easier to read. If you go changing the tab character to 4 spaces, that alignment is ruined.
Also a reason for not using proportional fonts.