I assume that's due to the stupid setting available in emacs or vi or whatever editor it is that actually encourages that behavior. The one where they've said "We want to indent to 4-space tabs. However, the editor is configured to print 8 spaces for a tab. Therefore, when we want to indent one level, we will use 4 spaces, and when we want to indent 2 levels, we will use one tab, and when we want to indent three levels, we will use one tab and then 4 spaces." And so forth. I'm convinced such an editor setting exists somewhere, because I have seen this nonsense in other projects too, even to the extreme of 2-space indentation. (Indent sequence: 2 spaces, 4 spaces, 6 spaces, one tab, one tab and 2 spaces, etc.)
No, not really a problem. I would accept extra disk space if this solution brought significant advantages, but I'm saying it brings drawbacks.
I use TextWrangler, the free sibbling of BBEdit.
Also, if I press the Tab key on the keyboard, it inserts a tab character. Even if I could tell the editor to insert spaces instead, I would not configure my editor this way, because that is not how I want to use my editor in every other text file that I edit.
Now I'm curious: What editor do other people use to edit their portfiles?
I'm just saying that you may like 2-space tabs, but I don't. If that's what we standardize on, I'll be unhappy. Someone else may like 3-space tabs, and they'll be unhappy unless we choose that. Why choose at all? Why not let the user choose with their editor's tab width setting? That's what it's for.