It's not the hackers, a good example of current Ddos activity is between the hosts of DayZ origins and DayZ Breaking point.
Origins creator is now attacking the Breaking point mod servers just because they were becoming too popular.
Also in the first week the Fragtard Arma 3 server was online we had some Ddos activity inbound to us, however this was just a lone wolf causing the server to have a higher ping but still function(As he ddos'ed with only 100Mbit while our server has a 1Gbit connection), but due to the high ping our playercount dropped from 40 to about 15 at that time so you can see what the results are
Popular servers are always good targets for a DDOS.
The main reason of DDos is to stop someones service's from working automaticly resulting in players coming towards you.