True, there are some things that are best done in C# like WPF, but that is not a sufficient handicap to truncate F# from the population of general purpose languages.
I actually don't see any issues with F#, it's more:
- The ubiquity of powershell and the ISE. powershell is installed on every server, and to step outside that means deploying a new compiler/runtime and its dependencies to production servers.
- Doing operational tasks is easier with powershell (in the short term) because the existing cmdlets for managing servers are provided with the language. An example would be bulk updating 500k users in AD (with complicated logic that compares data between 4 or 5 other systems)
- Using the Add-Type cmdlet to include F# libraries into Powershell requires a few manual steps that might break over time: https://tahirhassan.blogspot.com.au/2014/06/embedding-f-in-p...
- Awareness/ecosystem - powershell feels like its being used to solve all 'server related' operational problems at the moment, and that F# is used for apps. i dont think my team mates would appreciate me solving a problem in F# unless everyone was happy about the choice of language beforehand.. Same goes for them if they wanted use python, rust, prolog. etc.
The only thing vs. C# which I think it lacks is support of unsafe pointer arithmetic. Which I've never really used in C# either.
ADDED. You don't seem to share my preference for conversations that stay focused on one topic. Over and out.
Hint: Functional programming isn't a domain.