The point of flashing an LED with an Arduino is not to flash the LED, it's to get the tools setup and workflow working while learning the basics. It's the "hello world" of microcontroller programming.

I've heard this process called "flow flushing". With things like FPGAs it can take days to go from nothing to flashing an LED. Because the toolchain is large, complicated and opaque.

It sounds like the Javascript world have built large toolchains for large projects and have then cargo-culted into using the same toolchains for tiny projects when they don't have to.