again, "widely available" should not be intended in the general sense but as a much more precise industry term. "Baseline widely available" is defined[1] as a feature which has been available on all the core browsers (Chrome desktop and Android, Edge, Firefox desktop and Android, Safari on Mac and iOS) for two and a half years
I don't really care about someones phony definition of widely available. If it runs on 90% of user's browsers, it's widely available. I'll gladly make a web page that puts this definition online so that you can also reference it in discussions, if you want.
[1]: https://web.dev/baseline