I fail to see what problem F# solves that is not already done as well or better in Go, Rust, or Python, coupled with the wide acceptance and/or hype among other developers for those languages.
Rust feels like the closest thing to me in terms of overall practicality/ease of use.
I think F# does have a much stronger "in the browser" game. Yes, even a bit more than Rust, if you consider whole web applications and not just performance critical modules.
And some people and companies are extremely stuck in Dot.Net...
Sure I can write stuff in Go or Rust or Python but I don't see that any of those offer anything significantly better than .Net, including the support level, the quality of the IDE and even, God forbid, half-decent performance.
Sure I would choose another language for something that had to be super fast or perhaps headless but otherwise I would choose .Net every time.
Disclaimer, I have professionally used Java, PHP, C, C++ and C# but not Go or Rust.
IDEs for Python have improved a lot, and the more passionate Pythonists might fault C# for actually needing IDE tooling for being bearable...
I can see why you would prefer C# over PHP, C++ and Java for Web programming though.
F# came out well before Go and Rust and well in time to compete with Python's popularity. There were other factors that affected its adoption.
I think you should look again :)