Perhaps it's because you can easily bolt on CSP to the languages where it's popular? JS is single threaded, and Rust and C# don't have green threads. I conside

Perhaps it's because you can easily bolt on CSP to the languages where it's popular? JS is single threaded, and Rust and C# don't have green threads. I consider Rust to be an antithesis to your remarks because it has realoy good tools to prevent concurrency issues and yet still wants it. I think on a deeper level it's because there are times where the thread isn't really doing anything and is instead waiting, and that time could be better apent doing something else. That requires sync, either with callbacks, promises or sync/await.