As for why not use an icon font, we've actually outlined the research in details here: https://medium.com/claritydesignsystem/the-road-to-svg-and-c...
Maybe SVG should support hinting...
The icons look blurry on most zoom levels. On zoom 90% the effect is reversed and the left icon looks ok but the others don't: https://imgur.com/a/AeREO
As for why not use an icon font, we've actually outlined the research in details here: https://medium.com/claritydesignsystem/the-road-to-svg-and-c...