IMHO WPEngine is rent-extracting in the same way that AWS does with many open-source solutions. Customers want products not source-code and are prepared to pay for packaged value-added products compatible with Wordpress. But none of this revenue is going back to the developers and fostering the development ecosystem in any meaningful way. If opensource projects like Redis & Elasticsearch could have had developers hired from 8% of revenues from those AWS sales imagine how much better off those projects could have been.

WP Engine also acquired, and continues to maintain, projects like Advanced Custom Fields [1] and Local [2].

Local used to have pro features, which became free for everyone after the acquisition [3].

[1] https://www.advancedcustomfields.com/blog/reflecting-on-two-...

[2] https://wpengine.com/blog/better-together-wp-engine-and-flyw...

[3] https://localwp.com/pro-for-everyone/