Interesting post, there is however one main point about the agile process missing from the post, and maybe this just goes to show how many organizations are doing it wrong, but retrospectives are a large part that makes not just agile work but helps make sure a team as a whole can work together.

It is great if you can adopt ideal agile/scrum practices, but as the article alludes that doesn't always work for people. Retrospectives are a way for the team to reflect on their current process, on what works and what doesn't and to continually make the changes they need in order to be productive and successful.

Also, another side note. I have worked for organizations that both allow padding space in velocity for technical debt and those that constrict it. It works much better when the organization (I am thinking mostly managers, product, non-dev) know and agree up front to a set amount of time each sprint being spent on technical debt.