I understand why the idea exists. It just doesn’t seem to me that 55 out of 100 really indicates a significantly greater degree of public support than 51 out of 100.
But I also realize most people don’t agree with me.
It presumes a world where 40% of the public would support anything with a -D after its name and 40% would support anything with an -R.
Under that view, it's not 51/100 vs. 55/100, but 11/20 (55%) vs 15/20 (75%), which is a much more meaningful result.