Abandoning something takes more work than using it, since it adds the cost of a rewrite. If Airbnb adopted framework X that wouldn't make me confident in framework X -- they haven't even used it yet! If they used it for a long time that would increase my confidence in X (in the absence of evidence to the contrary). But if everyone else started abandoning X I'd take Airbnb's experience with a grain of salt. I get that Discord is able to do well with it, but that doesn't mean everyone is able to do well with it depending on their needs. And who knows, maybe Discord is having just enough trouble that it hurts but too little to switch.