Sure, but you can still find plenty of info on it by searching for .NET Framework or .NET 4.6. All the documentation is still available. Its just not in the spotlight any more.

Hi, it's me, the intern refactoring the spaghetti .NET core backend. I'm not in a basement though. AMA

Not an intern, but this week I've unraveled some mysteries in ASP.NET MVC 5 (framework 4.8). Poked around the internals for a while, figured out how they work, and built some anti-spaghetti helpers to unravel a nested heap of intermingled C#, JavaScript, and handlebars that made my IDE puke. I emulated the Framework's design to add a Handlebars templating system that meshes with the MVC model binding, e.g.

@using (var obj = Html.HandlebarsTemplateFor(m => m.MyObject))
{
  Name: obj.TemplateFor(o => o.Name)
}

and some more shit to implement variable-length collection editors. I just wish I could show all this to someone in 2008 who might actually find it useful.

It is very much still supported and will be for a very long time.

You just shouldn't start any new products using it.