The post is essentially reminding people that XML doesn’t magically equal openness. A schema can be “unnecessarily complex, bloated, convoluted and difficult to implement”, and in the case of Office 365 the spec runs to “over 8 000 pages” and uses deeply nested tags, overloaded elements and wildcards. The result is that only the vendor can feasibly implement it, which eliminates third‑party implementations and lets the vendor dictate terms. The rail‑control analogy in the article makes the point well.

What isn’t acknowledged is that a lot of that complexity isn’t purely malicious. OOXML had to capture decades of WordPerfect/Office binary formats, include every oddball feature ever shipped, and satisfy both backwards‑compatibility and ISO standardisation. A comprehensive schema will inevitably have “dozens or even hundreds of optional or overloaded elements” and long type hierarchies. That’s one reason why the spec is huge. Likewise, there’s a difference between a complicated but documented standard and a closed format—OOXML is published (you can go and download those 8 000 pages), and the parts of it that matter for basic interoperability are quite small compared with the full kitchen‑sink spec.

That doesn’t mean the criticism is wrong. The sheer size and complexity of OOXML mean that few free‑software developers can afford to implement more than a tiny subset. When the bar is that high, the practical effect is the same as lock‑in. For simple document exchange, OpenDocument is significantly leaner and easier to work with, and interoperability bodies like the EU have been encouraging governments to use it for years. The takeaway for anyone designing document formats today should be the same as the article’s closing line: complexity imprisons people; simplicity and clarity set them free.