Because Meta is not the default to everything.

I've personally been hoping for something like this for a while now. Especially a toolset that is not just targeting yet another SaaS or LLM or social media clone interface.

I don't know if you ever used Draft.js that FB put out some time ago, but it was a horribly buggy monstrosity that was a heavy lift to move away from. One could not write several paragraphs and edit them without losing a lot of work. I wouldn't touch "Lexical" no matter the marketing they put on top. I wouldn't be half as critical if it wasn't one of the wealthiest companies on the planet known for injecting billions into black holes while they raid every area of your life they possibly can for data to be used to manipulate socio-political matters everywhere. If they're going to do that, and release open source libraries, then at least make them good enough to be seductive. They aren't.

ProseMirror and seemingly WordGard have real thought and care put into them by people who have long made the DOM/developer experience and the writing experience priorities– not just their "mind share" for whatever dark purposes drive companies like Meta.

Have you made that conclusion after thorough examination of the open-source code base?