Reddit has been running ads for over a decade. If they are this far in and not doing basic fraud mitigation, something is wrong.
Also we don't know if they are doing basic fraud mitigation. It's possible they are doing plenty of fraud mitigation, but that it's just not advanced enough.
Every business is obliged to be ethical, vigilant against deception, and not blatantly lie, no matter what size they are. Even if you could make an argument like this, reddit was already pretty big ten years ago. That's why they started running ads.
Not that they need to change, i like the simplicty of their ads