Comment by Timwi

I'm not the OP you're replying to but I think you missed some of their points.

1) multiple outlines: with your strategy, you can no longer edit the shape as a single shape afterwards.

2) varying thickness: it sounds like you're thinking of thickness varying abruptly from one line segment to another, but remaining constant throughout one segment. I would like a feature where the stroke width varies continuously from one vertex to another, that is, get smoothly thicker or thinner.

3) you can only have rounded corners on every vertex or no vertex of a shape. You can't choose individually for each vertex.

I think these are all features that SVG would benefit from adding.