To play the devil's advocate: it might not be a one size fits all solution. When you're at Microsoft and can just walk up to the bar researchers and programmer

To play the devil's advocate: it might not be a one size fits all solution. When you're at Microsoft and can just walk up to the bar researchers and programmers in the world, maybe. When you're at some corporation where you have to spend half a day on the phone to get your computer unlocked by the desktop support and request to change a config on a web server becomes a ten foot long email chain about whose fault it is that we need this change, I don't think people have any motivation to modernize piece by piece. Then there is the issue that you'll have to explain why part of the application is in .NET core and part is in dot net framework 3.5...