Because in a few months, people won't remember the details, but they will remember "the time the Wordpress guy abused his influence to damage the Wordpress ecosystem".
Your original comment was speaking in general terms, about all Sharepoint services. Not your specific deployment. Details matter or your argument falls down.
As for concurrency, read my comment again, I use the specific word.
These assertions are just not true. I'm working right now on a document with coworkers, concurrently, via a Sharepoint server. Change tracking is enabled and can even be enabled by default by the Sharepoint admin.
I share a lot of your sentiment about open formats in previous comments, but this is classic FUD and demonstrably wrong.