'DDOS' means something really specific to us. Is someone trying to knock your web site offline? Great, that's a Denial of Service attack, frequently abbreviated as DOS. There are many types of DOS, with DDOS being only one of them.
There is nothing more extreme or 'hardcore' about a DDOS versus any other form of DOS. Any DOS is either effective or it's not. If it were ineffective, it would no longer constitute a DOS.
It's like some people use the phrase 'carpet bomb' to indicate some extreme form of bombing, when there are plenty of forms of bombing more extreme than a carpet bomb. Done correctly, a pipe bomb is more effective than a carpet bomb. Done tactically, a cherry bomb is more effective than a carpet bomb.