I was reading this article here which made a lot of sense. There was a bit of confusion on my part that was touched on as originally I assumed that ASP.NET 5 was the newer version of ASP.NET 4.6 while in fact it was a whole new branch of the feature. With branch I mean, ASP.NET Web forms, ASP.NET Webpages, ASP.NET MVC, etc… where although they are all preceded with ASP.NET and share some similarities, they are pretty different and each are designed to work in different scenarios. The same is true for ASP.NET 5 / ASP.NET Core 1.0, I.e. a new branch.
Additionally, .NET Core 5 is now .NET Core 1.0 which also better communicates the maturity of the library.
The above image was taken from this article here.
Also a nice video of this change and details.