Thoughts on viewBox property

I've been experimenting with react-vis components library and modifying it to pass a viewBox property all the way down to the svg element in XYPlot.

The results so far have been quite promising:

• The elements inside the graph can easily be deployed in relation to each other using the internal coordinate system
• Sizes can also be expresses in a way consistent with that system
• The SVG scales appropriately, and it can be combined easily with flexbox.

So my question is: why is it that this doesn't have support out of the box? Is there any drawbacks I'm not noticing.

Thanks.