Yes, of course.
Eliezer said a lot of things.
I'm just saying that it is intentional that you can't vote on the comments on someone's profile page. (I found the relevant entry in the issue tracker.)
I was about to say that if sometimes the buttons do appear then it's a bug, but it turns out that this behavior has been changed:
Users with sufficient karma can downvote on the userpages of people with less than a certain percentage upvotes.
What's up with that?
In a discussion thread, I can karma vote on anyone.
But if I select a person to see all their posts, for some people, karma is disabled while looking at them, and for others, it's not disabled. Same thing if I look at their posts under the list of all my posts.