It's more accurate to describe it as a subscription model. SaaS typically means that the software is delivered as a service (hence the name) and is not installed locally. That's not the case with most of Adobe's products--although they do have SaaS elements (e.g. cloud storage) of various sorts.
David Wadhwani was responsible at Adobe for the switch to the SaaS business model. Because of that he got a job as CEO of AppDynamics, to make them ready for an IPO.