You are right (the -t flag on Windows systems is much less capable of overwhelming a target, from Wikipedia) Now most DDoS attacks are generated from a string of computers.
A DDoS is just repeatedly attacking a site with downloads to its server. The server then shuts down to accept these files, which do nothing.
A DDoS is normally caused by a botnet - Botnets are groups of hacked computers that will send data to a server on demand - It requires about 10 gbit/s to take down the minecraft servers - Honestly - Pinging them with 32 bytes won't do anything unless 41,943,040 (4X the population of minecraft) did it at the same time.
