Because a big picture looks pretty sometimes?

Not sure what you think "having an SVG renderer in memory" means exactly, typically the way an SVG renderer works is that you give it a huge chunk of memory and ask it to draw pixel data there from the SVG file. So even though the SVG is small on disk, rendering a 1000x1000 image from an SVG is gonna need a 1000x1000x3 byte pixel buffer (assuming no transparency or HDR shenanigans)