Just picking a nit, but it's not multi-core that JS can't be used; Node has some solutions for leveraging all your cores (multiple node processes, basically. PM2 and its ilk). It's specifically CPU bound problems, where the benefits of JS' concurrency model can't shine.
Picking a further nit: the key difference is that most other languages can share memory directly between threads, whereas JS can only pass messages between threads (which requires copying data, and usually serialization/deserialization)
Workers have "transferable" objects that in theory avoid copies, but still there's a world of difference between coarse-grained message-passing style, and fine-grained data parallelism you can get from something like rayon.
JS "can" do a lot of things if you know how, and cleverly implement and optimize the code, but it's a Turing Tarpit. You wouldn't implement a video codec in JS. You could, but it's not the best language for it.
