That it was a closed runtime full of security issues wasn't the reason it was rejected by the open web community, or even rejected by Steve Jobs from the Apple ecosystem. Closed runtimes and security issues have always been warmly embraced by the web.

It's just that supplying binaries to the web is less open than supplying html and js. It's not an especially strong argument, less so given how minified and uglified JS is nowadays, but that's what it is.