Hah, we've definitely thought about that possibility. Fortunately we do have a few things in place to prevent the most obvious abuse cases, but we need to get popular first!
Right now it's fairly basic: we recommend you offer a limited discount (for example, 30% off for three months) and by default a customer can only accept one offer for their lifetime. That would at least minimize most of the risk.
On the roadmap are plans to target offers based on segmented customer data (lifetime value, etc.) so even if you did try to follow a trick posted on Reddit, it might not work for you!
I was immediately thinking the same, but I'd assume there are certain rules in place for when users are eligible for a discount and the amount of the discount.