[joshstrange]

People who want to astroturf, from everything from products to politics (though honestly probably more for "products"). Reddit is well known for being one of the few places you can "trust" product reviews (that hasn't been fully true for a while now but it's still valuable). If a near-0 karma and/or new account says "I love X product" then they can sometimes be downvoted/called a shill but an account that's a couple years old and has decent karma? Looks like a real person.

That's at least the explanation I've heard many times.

[MostlyStable]

Once you cross the extremely small karma barrier needed to get your comments allowed/not be rate limited...whats the point? I use reddit for a lot of recommendations/research and I have _never_ checked the karma of a user after reading their comment.

[TylerE]

To appear trustworthy.

Account says buy bitcoin - user checks history and sees 7 year old account with thousands of posts, many highly upvoted, so assumes source is sane and not astroturf.

[MostlyStable]

That's my point though: how often do people do that check? I don't think I personally ever have. Maybe I'm just weird though? I tend to not just go with a single user/comment/thread, but rather try to find multiple different answers and gestalt from there, so individual trustworthiness is less important.

[xapata]

You have to remember that with spam, they're looking for gullible people, and the marginal cost of the spam activity is extremely low. To some extent, the Nigerian prince scam works not in spite of, but because it's nonsense.

[paulmd]

there are definitely browser extensions that will call the API to check account age and highlight suspicious accounts, that's how "checking" generally happens except in egregious cases.

[TylerE]

Obviously it's higher than zero, else the market for accounts wouldn't exist.

[andybak]

Isn’t this begging the question though?

I.e., the thing you have just stated is exactly the thing we’re trying to figure out.

[TylerE]

No, because we're talking about a phenomenon that indisputably exists.

[giantrobot]

Karma on Reddit is used as a proxy for "this user makes good contributions". At smaller scales in the past this might have been a useful proxy but when a pithy joke on a huge subreddit can get thousands of upvotes it's not longer a good proxy. But since people still use it as a proxy astroturfers wants as much karma and activity as they can manage because it makes the account look more realistic.