The author of the op-ed is a devoted editor but seems almost totally ignorant of how development is conducted. The Foundation has been doing transparent quarterly/yearly roadmap planning alongside their annual plan / budget cycle (which is shared all publicly). On a shorter timeframe, they are pretty serious about Agile/Scrum. You can see on https://wikimediafoundation.org/wiki/Staff_and_contractors that today they even have a team of half a dozen full time Scrum masters. If what he thinks is missing is serious, detailed planning, he's sorely wrong.
The platform (MediaWiki) is still a FOSS community so you can find project requirements docs/roadmaps all over mediawiki.org, all the bugs on Phabricator, follow along on mailing lists, and even see commits on their Gerrit instance.
Agile isn't my cup of tea personally and I could grok criticisms of the organization's software output (ignoring the fact that they're buried under 10+ years of technical debt...), but it takes minimal digging to find all their plans and timelines. I would venture that the author chose not to dig into this because he, like a lot of entrenched old school editors, viscerally hates some of the past attempts to make MediaWiki a modern collaboration platform, such as building a WYSIWYG editor and a threaded discussion system to replace wiki talk pages.