so that every programmer can have his own indent level, established by his own preference for hard tab size.
I've tried that with a team, where instead of arguing over the indent level we all just kept our editors to the tab width of the indent level we wanted. The result was a worse mess.
Editors are smart about indenting source code. Sometimes, for example, there is a reason to indent a certain number of spaces, say four, independent of the default overall indent level. The editor may then insert four spaces if the tab width is eight, or a tab character if the tab width is four. As a result files never looked right in more than one person's editor and people had to reformat the entire file before they could work on it. Instead of avoiding the problem of indent level, we got to argue about indent level _and_ tab width.
There just wasn't any solution except to not use tab characters and then we could agree to compromise on what indent levels to use.
-- sidney
