DO has sometimes been accused of overselling capacity and then terminating services when they are fully used. I have never actually heard a first-hand account of this, but I assume that is what the parent is talking about.
I'm not sure if this is what you're talking about, or if the scale just wasn't a problem, but anecdotally I've (accidentally) pegged a 5$/mo instance for at least a month without any issues.
EDIT: I do know that DO/Linode/(maybe vultr) have blackholed IPs during large scale DDOS attacks, simply because they don't have the infrastructure to mitigate it, and you affect their other customers.
