We could do it that way, but my goal here was trying to remove hardcoded coupling between our "Reach" layout and the way the components/graphs work. For example, before all the line components had `config.target` defaulted (and hardcoded) to `.gl-framed`, meaning that if we ever changed the layout, everything would break. So I removed it. 

Now if we default to the `svg` element we must specify `target` in every `graph.component()` call that we make, which becomes cumbersome, so I added the `primaryContainer` config to be used as the default. Maybe I should check that the primary container config actually exists before setting it on components, and if not I can leave the component target as null which will force rendering to the root `svg`. Does that sounds like a good solution to you?