Ddosing is the easiest thing ever. I personally know people who do it 24 /7. I personally hate it and am disgusted by it.
Runescape servers are ddosed often aswell, as in particular worlds. Prior to F/T release again, w137/65 was ddosed everyday for 1 - 3 hrs.
It can be done by a 11 yr old, provided they have $$, or provided they are smart enough to spread their botnet and or host a few shells on a dedi, which requires no $$, rather brains and effort.