Someone doing maintenance work on C# project might find code going all the way back to C# 1.0.

Also improvements to low level programming, being done since C# 7, a few semantic changes, aren't for removing boilerplate code.

Then since a language is useless without its standard library, there have beem plenty of changes on how to do P/Invoke, COM interop, development of Web applications, and naturally knowing in what release specific features were introduced.