Having run a website on launch day where we've been overwhelmed with messages from MySQL such as "Too Many Connections"
I can definitely say that normal traffic can cause "denial of service" of both databases and websites, if they aren't configured and structured to handle such a load.
No matter what this sensational site says, it wasn't "hacking". I won't go so far as to say there wasn't automatic posting involved, but a true denial of service attack is much more reliable and still relatively easy to do than a partial one that only affects a database ... how would you know that the FCC's databases would fall over under load in advance of your "attack"?