Not to nearly the same level. Like any major site, I would guess the majority of HN readers do not comment, or only comment rarely. Losing karma for upvoting

Not to nearly the same level. Like any major site, I would guess the majority of HN readers do not comment, or only comment rarely. Losing karma for upvoting means you need to comment if you want to upvote, and I suspect many readers will simply choose not to participate in either activity rather than try to maintain a positive karma balance.