That is interesting. I don't remember getting a lot of starbursts with wider apertures so you have prompted me to go back to a shot that I took with what I thought I knew in mind:
Unfortunately, I didn't record the exact aperture for that shot (manual lens) but it was small (at least f/16) because I thought that was the key factor. I wonder if, instead, the rule is that bright lights in reasonable focus form starbursts? You can see a prominent one where I was focusing and hints of a starburst on another further back and near the right of the picture. The relatively dim lights of the Christmas tree and the lights that are well outside the sharp zone are not affected.
If that is the case, then perhaps the small aperture theory appears to work because there is more chance of catching a strong light in focus rather than at a point where "bokeh" steps in and rubs out the star lines?
Wulf