OP could have easily found out why FF failed to build on newer Rust, which is in fact due to its use of experimental/unstable features which it enables through

OP could have easily found out why FF failed to build on newer Rust, which is in fact due to its use of experimental/unstable features which it enables through a flag that is only supposed to be used for bootstrapping Rust. Because it effectively opts out of any stability guarantee, FF only builds on certain Rust versions. But instead of taking a moment to read and understand the error messages, or ask the community for help with understanding them, OP chose to publish and popularise a blog post without including the error messages (or any context that would help anyone to make up their own mind based on actual facts). Courage is not the word I would use.