I'm working on migrating an ASP.NET 4.0 application right now, and it's basically stuck in the past.
Physically, yes, it could be updated by the developers to work on .NET 6.0, but no manager will ever fund this. They don't understand the benefits, and no amount of explanation will justify this effort in their minds.
So Microsoft basically stranded their customers on an iceberg floating away from the shore that is very slowly, almost imperceptibly melting...