I'm not sure if it's true, but there were talks about WPEngine devs basically not being allocated any dev time on WordPress anymore (whereas Automattic devs spend tens of hours a week on the actual OSS project). That was one of the catalyst behind the whole drama where Matt called them out basically on stage during a conference talk. Which was just before (or at the same time) as he started talking about the royalty.
Now, again Matt's behavior has been super weird since he basically failed at articulating his position well, and his PR has been catastrophic.
But the fact is WPEngine still does not contribue to WordPress. That is their right, but everything matt has been doing is also "legal" and within his (and his company's) rights.
I think it's the other way around: the (false) claims about WPEngine not contributing became a thing because they refused his demands to direct 8% of their revenue into matt's private-equity-backed pockets.
It would make no sense otherwise: "you aren't contributing to the community, so contribute to my for-profit corporation instead"? If matt really cared about the community*, wouldn't the appropriate demand be for WPEngine to contribute 8% to the community, instead of to matt?
*: yes, I recognize that, in reality, matt's repeated actions harming the community in service of himself have made clear that he cares more about himself than the community.
Also, the community (in terms of development) is basically automattic and... that's it. That's the whole problem! But again, I completely agree that the royalty request was extremely weird especially considering the supposed separation between WordPress.org & Automattic
