Don't mix mainstream adoption at the same level as regular JavaScrip and Typescript, with availability.
Microsoft would wish Blazor would take off like React and Angular, in reality it is seldom used outside .NET shops intranets in a way similar to WebForms.
Lots of people are building Blazor applications:
https://dotnet.microsoft.com/en-us/apps/aspnet/web-apps/blaz...
> not most people aren’t using a high performance spreadsheet
A spreadsheet making use of WebAssembly couldn't be deployed to the browser if WebAssembly hadn't taken off in browsers.
Practical realities contradict pjmlp's preconceptions.