Yes, I work with vector art (almost exclusively in my business). But with a die-cut style decal, there are limitations to how small the machine can CUT two lines close to each other. If the machine is making a cut, then has to make another cut parallel to the first one (by only a few hair widths) the decal material will just tear as there isn't enough surface area to hold it in place. With large decals this is not an issue as the lines become much thicker when enlarged.
Maybe a video would help explain:
http://www.youtube.com/watch?v=zq6RQbziWwo This is an example of very easy to "weed" decals since the letters are very thick. If the letters were very small/thin, there would be issues trying to make them as the letters would just want to come off the sheet when peeling away the excess.