I don't think that's true by and large. C# started purely object-oriented, and it progressively started extending it's usability into functional programming domains (pattern matching, null coalescing, tuples, lambdas), lower-level code (return ref structs, memory spans), and relational programming (LINQ).

So basically, C# is incorporating diverse programming idioms with different strengths from OOP so you can choose the right one for the problem at hand.

In the past they released every three years. Now they release every year. So it is a piecemeal. But there are very strong themes active right now

- simplification for newbies (global usings, top level statements)

- better memory management for performance (ref, readonly, in, value task, custom task providers, ..)

- bring functional structures loved by many (tuples, records, pattern matching, generic math)

- code generation for aot and simplicity (code generators)

- and always productivity (many small things)

In the past we had themes about asynchronity, linq, generics (think also co/contravariance), etc.

I do once a year a training for my fellow engineers. The churn is not too big if you keep up to date once a year and start using it a bit.

A lot of the improvements are just logically extending the language to remove arbitrary restrictions. That's what most of C# 10 and 9 appear to be. So most of the features you wouldn't go out of your way to use, but instead stuff that used to be impossible is now possible. I can't say that I've ever wanted a generic attribute, or a constant interpolated string, but if I did want them, I'd be surprised when they didn't work. C# 8 was the last major new language features.