Basically, Reddit accounts can be valuable if you want to manipulate viewpoints or push a product.

Older accounts (more karma, active for a number of years) can be bought and used to post comments which support a certain rhetoric. Now that rhetoric can be a product, or a political viewpoint (think Russia, hyperreality and perception management).

Users with RES can view the account info at a glance - a comment from an account 4 years old with 360,000 comment karma may hold more weight to the person reading it than a day old account with one comment, if that makes sense?

It all sounds a bit tinfoil hat, but if you do some research its less conspiratorial than you might think.