We can't pick and choose which contributions are valid and which aren't. WP Engine spend money on the development of WPGraphQL a free plugin, WP Engine spend money on the development of Advanced Custom Fields which they release for free for millions of WordPress sites to use... of course they're not doing that out of some altruistic moral crusade, of course it's a clear calculus about the benefit to their bottom line, but that doesn't change that they're contributing.
The "Five for the Future" contributions are specifically about contributing to WordPress Core, which is owned and controlled by Matt Mullenweg: you're playing into Matt's absurd narrative that the only valid contribution is one that is made to something under Matt's control.
I think WP Engine are Private Equity leeches, I have zero doubt about that, I wish that they were to contribute more but that's the deal with Open Source software, that's what we choose to allow by releasing Open Source software. The moral obligation we have when we use Open Source software is to respect the license, Matt had the choice about the license to release WordPress under, he made the choice for it to be GPL.
dhh is more eloquent and authoritative than I, read these if you need further convincing:
https://world.hey.com/dhh/automattic-is-doing-open-source-di...
https://world.hey.com/dhh/open-source-royalty-and-mad-kings-...