There is some evidence here that hiding it to avoid egotism isn't worth the loss of function: http://news.ycombinator.com/item?id=2430542
See, respondents to the comment had to manually create a child comment "+ 1 for this idea!" to get their message out. That's not efficient, organized, or quantifiable.
I also wonder how much having no comment scores even contributes to eliminating egotism and hive-mind behavior.