It's been done many times. Mozilla had XUL. Internet Explorer had XBAPs (XAML Browser Apps) [1]. Android has an XML UI language. Java has FXML, which IMHO is th

It's been done many times. Mozilla had XUL. Internet Explorer had XBAPs (XAML Browser Apps) [1]. Android has an XML UI language. Java has FXML, which IMHO is the cleanest and nicest of the lot. It never works. Same reason as to why adding non-JS languages never works: because making a GUI toolkit or implementing a language is a huge amount of work, other browser makers refuse to get on board because it'd mean they're playing catchup. Then web devs refuse to use it, because not every browser supports it. The only acceptable way forward is to gradually glue lots of small things onto HTML, and see which ones get implemented by the others. Because this is such an incremental and random process you end up with a pretty inconsistent platform that lacks a lot of stuff you'd intuitively expect. [1] https://learn.microsoft.com/en-us/dotnet/desktop/wpf/app-development/wpf-xaml-browser-applications-overview?view=netframeworkdesktop-4.8 https://learn.microsoft.com/en-us/dotnet/desktop/wpf/app-dev...