[kemayo]

In the abstract, yeah, that'd probably be fine. Maybe not 100% legally -- the injunction that WP Engine got seems to imply that blocking one specific competitor from using the infrastructure might not be cool -- but if it was a restriction that was in place from the beginning, it'd probably have been acceptable.

It's mostly that WordPress maintained that infrastructure for a very long time without having any sort of restrictions on who could use it -- whether you're a self-hosted WordPress site, or you're using some sort of managed hosting (like WP Engine or WordPress.com). Plus it's literally hardcoded into WordPress to use it; you can't change that without maintaining your own patched version. So everyone involved in the WordPress community viewed it as a general public good for all users of WordPress... and it suddenly getting weaponized didn't play well. For one thing, it put up a lot of people who were just users of WordPress as collateral damage.

(And the cost of the infrastructure doesn't seem to have been one of Matt's complaints, in general. If it was, and he'd been up-front about that, I suspect reactions might have been different.)