nothing. I'm in the social media business and I can tell you it's very easy to make 5 figures/month gaming reddit(as an individual operation) using farmed accounts and it's been going on for years. Not necessarily with stock schemes. they got next to none security when it comes to stuff like this. agency that I worked at a few years ago literally had thousands of aged reddit/twitter accounts in their portfolio. there are whole apps available for sale that manage your reddit farms including fingerprint faking, proxy management, captcha solving(outsourced to developing countries), etc. the market for it is pretty huge.

Edit: hints = look at porn subreddits, /r/entrepreneur, stock subreddits. By the way, some of the moderators are making a killing too (by promoting their "own" people)