Ask HN: Suggestions for cutting down new account spam

Hello, HN. I was just looking through the New page to see if there were any interesting articles. I have showdead enabled, so naturally I saw the large amount of [dead] submissions. (Out of 30 posts, 17 were killed, only one from a regular member.) Realizing that most of these were blatant spam posts, I checked out the profiles under which they were submitted, and I noticed a couple trends. The accounts had either been created within 24 hours for the purpose of the submission, or more common, the accounts were many days old (often over 100) but obviously used only for these spam posts, and only had 1 karma point.

If the server doesn't automatically identify and kill these posts, then it must be a lot of tedious work for admins to manually kill these posts (and maybe the server does find them on its own. If that's the case, then this post may be irrelevant). I thought about it, and came up with a possible solution. What if new users weren't allowed to post until after they earned 10 karma points? This would bring the level of work required for the spammers to make submissions above the potential return, reducing the number of attempts, clearing up the new page (for showdead users like myself), and hopefully ease the workload of our wonderful admins.

My questions for you:

Is something like this already in place? (I imagine not, because there are some users who create anonymous accounts just for a specific Ask HN post, but I could be wrong.)

Are there any other suggestions from HN users to clear up the number of posts from spammers? Is this a practical solution? Would it discourage new members? Would spammers just find another way around it?