Your assumption that you need to develop or even use malware to commit these attacks is incorrect. As the article eludes to, most "script kiddies" would be using simple reflection attacks like those utilized by anonymous. This would equate to changing a few lines in a TCP or UDP packet and mass spamming 3rd party site to elicit a flood of responses. This is pretty simple for any 13+ year old with visual basic and some time. Large bot nets rented out for attacks are clearly more dangerous and I would assume (hope) the FBI does target the malware creators and distributors.

Folks sometimes start as consumers of ddos services and at some point realize they can run their own service and make money, buy API access into other booters to begin (reselling but the customer doesn't know) and then they figure out how to build their own infra (dedicated servers, front end, payments etc.).