The argument for tabs really goes that time is spent much more on reading code than authoring, so it should be optimized and customizable (tab width) for the reader.
Admittedly this is something of an edge case - how many languages other than Lisps involve alternating layers of indentation and alignment? The more common C like languages don't suffer from this at all.
At this point I'm largely convinced that more or less all of our tools, languages, and conventions are poorly thought out, brittle, and inelegant. /rant
(setq zwei:*indent-with-tabs* nil)I think the ideal situation is a language with an official or at least commonly accepted formatter, so that existing and new projects will essentially always follow the same style and you never have to think about it. Like "go fmt" always using tabs. I don't like tabs, but I like that kind of enforced consistency way more than I dislike tabs.
That's also why I like using opinionated third-party formatters like prettier and black. Combined with pre-commit hooks, you almost never have to think about style and can just focus on the code. Plus diffs are cleaner.