WordPress has problems. Big parts of WordPress sucks. But WordPress-the-thing is hard to argue with. It doesn't demonstrate a need to conflate sites with apps (maybe that impresses low-information folks but as a developer and a content creator I am left asking "so what?") and it doesn't need to hide its brain as a revenue model--they make a lot of money despite WP/WPMU both being open source. And somebody who has spent a decent chunk of time and money wrangling CMSes--I don't see a ton of value to a CMS I can't audit and can't just run myself. The `and` is important there. I'm happy to pay for support--and sometimes for operationalization, I've paid WPEngine a decent amount of money over the last few years--but I pay for support once I've validated the use case.
Perhaps I'm not the target audience. But I'm asking "why would I use this?" and coming up kind of empty. Beyond that, what does trouble me is the way in which you're intensely attempting to slag WordPress (which, tbh, rings hollow; "flies don't bite a man who's sure of himself" and all that). You can use WP as an API these days, and it's not bad. Not perfect, but not bad. But you can also do that with other headless CMSes, and I'm not really catching much differentiation between CosmicJS and those, either? The whole thing is coming off like low-information-targeting to me and that immediately makes me ask "OK, where's the grift?". I assume that isn't your intent, and I'm trying to give you the benefit of the doubt. But that's kind of the message I'm picking up here, and that might be something to work on.