Beyond code and money, both of which I believe they contribute - though apparently not enough to satisfy Matt Mullenweg - you could argue that they offer a very straight forward distribution/adoption channel in terms of straightforward infrastructure.
I hate WP Engine - having had first hand dealings with them after they acquired a company I’d spent tens of thousands of dollar with - but nonetheless I fee like there’s probably a pretty strong argument that simple straightforward Wordpress hosting means more people use Wordpress which strengthens the overall ecosystem.
When I first started using Wordpress there was a steep learning curve to get it configured correctly on hosting where stuff wouldn’t break.
I used to pay someone to do that for me, and when they gave up doing that I moved to Flywheel (which was later acquired by WP Engine) and suddenly all of my previous problems with Wordpress from a hosting perspective vanished.
It just worked and the Flyhweel support team was amazing and would even unofficially support the wider implementation of Wordpress (“I changed this and now that thing has broken… I know it’s not your fault but any suggestions?” “Hey, here’s the problem, plus we have fixed it for you!”)
That made me stick with Wordpress for years and build out more sites in Wordpress and recommend it to friends and clients.
Most small businesses (which represents the majority of Wordpress users) don’t want to have to think about hosting: in the same way they expect their mobile phone service to just work, and email to just work, they need Wordpress to just work.
Whatever issues I have with WP Engine they offer a very straightforward “forget about it” service for running Wordpress which ultimately means more people are likely to use it.
On code contributions, I believe the accusation was that the amount of developer time they fund is tiny relative to the size of the company.
I've not seen numbers comparing other significant WP users to them, though, only comparing them to Automattic itself, which seems a bit apples to aardvarks to me.
At a minimum a plugin that Wordpress was forced to “fork”.
They have an equivalent of 1-2 full time people working on it, they sponsor the WordPress conference, and they make a couple really important plugins almost everyone uses
Both. Matt just does not think they contribute enough. Either that or he is angry that they are more successful than his own company.