Although I love Kanban this article is only half right. Scrum and Kanban solve two different problems and you might encounter either when developing SaaS. Let's get down to first principles.
Scrum is a batch oriented process. Batch processes are useful when the outcome of a process is uncertain and requires inspection and reconfiguration of the inputs after each batch until a stable and predictable process can be produced and the variables understood.
Kanban is a throughput oriented process. It is useful for reducing waste and optimizing for consistent and high output in a process where the inputs are already well understood and the output is of a more consistent quality.
You can then imagine how at the start of things when you aren't sure how everyone is going to work together well, or when you introduce a new paradigm or technology to the mix, Scrum might make sense.
You can also see how a long running SaaS endeavor with incremental upgrades, no major changes to staff or technology, could use Kanban to increase throughput and reduce waste.
For more information please see the fantastic "Process Dynamics, Modeling, and Control" who's author was consulted, ironically, in the very first Scrum book from Beedle and Schwaber.
The lack of science and first principles in the Agile space is why people say "agile is dead" and Agile coaches are treated like hacks.
This is my plea for more science and rational thought.
Also, David can split hairs all he wants about this (as agilists love to do) but the process theory around this stuff was laid down long before he graduated high school.