Microsoft has never taken it seriously, often releasing Visual Studio with broken F# support. It's fine for something you want to tinker with (like say Elm), but not something that's easy to sell to engineering managers when starting a new project.
Imho the bigger problem is that the C# language designer continue to not take F# into account. Structs and SUM types could be a shared MSIL story perhaps.
It is a predominantly community-developed language. Microsoft contributes engineers to ensure that F# works, slowly evolves and is able to consume all the new APIs introduced in C#, while community drives the evolution of F#'s own features. You can write your own RFC, have it pass through the review, get signed off by Don Syme and then, once approved, implement it (or have it implemented by someone else). Each new release usually has multiple features driven by F# community this way.
Give it a try and if you have questions - feel free to ask them on F# discord.