I disagree with this, you can sell F# to C# developers - things like type providers for SQL checking their query strings in compile time and no extra build step to produce SQL type definitions vs monstrosities such as Entity Framework... if they've been burned by ORMs to drop to stuff like Dapper they'll love F# type providers.
Immutable data is also becoming a common pattern even in C# but it's tedious as hell to write.
Functional programming is also seeping in but again tons of boiler plate.
Biggest problem with F# is that it has it's own warts + it's a big upfront switching cost and a steep learning curve but it offers many marginal improvements - when you sum those improvements it ends up being worth it IMO but that's a very hard sell.
Immutable data is also becoming a common pattern even in C# but it's tedious as hell to write.
Functional programming is also seeping in but again tons of boiler plate.
Biggest problem with F# is that it has it's own warts + it's a big upfront switching cost and a steep learning curve but it offers many marginal improvements - when you sum those improvements it ends up being worth it IMO but that's a very hard sell.