A concern regarding post value

I admit I am relatively new to steemit, though I've written a few posts about my observations and shared some experiences and speculation.

Please correct me if I am wrong, but what is stopping someone from essentially having a bot army of voters?
I do understand an upvote doesn't necessarily increase the value of a post (I'm not entirely certain what does, but if the system can be gamed at all you know it will be.

Entity 1 creates an account, and creates several bot accounts
They go about making sure the fake accounts have enough "steem cred" for their votes to mean something, then switch to full bot mode where these accounts simply upvote posts of entity 1.

If necessary, each bot can also have a category of news, or memes, etc that it will post occasionally as needed to maintain activity.

Everyone in the bot web can vote for each other to keep their posts looking beneficial, in some algorithm so it is not immediately clear they are just self voting.

Now, does this directly harm steemit? Perhaps not, perhaps yes, as someone is basically trying to just maximize any value they can get from the system, which I assume does detract from other people and their posts who may be of more value. It may not even be a high impact, but multiple people utilizing such a system would be parasitic to steemit and, besides leading to chains of self voting and posting nonsense, would most likely lead to 'real' people being drowned out.

Alleviate my concerns, steemers. I am not trying to sound like a doomsayer, simply voicing something I am curious about how it may be avoided.