I feel that, if this is the reasoning it's becoming more prevalent, then it should be reeled in a bit. Politically charged topics seem to rarely bring in good-faith discussion I have come to expect from HN.
Yes! No story makes it to the front page unless enough people upvote it on the "new" page. Thus, upvoting a new a story gives you much more editorial influence over the contents of the front page than upvoting a story that has already made it there. (And it takes fewer people to flag away an off-topic story while it's still new.)
Another perspective: By browsing the front page, you're looking at stories that other HN readers find interesting. By reading the "new" page, you have the ability to promote stories that you think are interesting.
As an example, the karma system at Reddit looks fine on paper relative to #1, but #2 is what created the phenomenon of meandering threads full of single phrase bad puns. The users are converging on a local maximum gain of esteem via upvotes, per unit of effort as measured by post length.