> It's like if we discussed writing a network app in Python and someone said that the GIL was a problem. Technically, there are python implementations that don't have that problem, but in practice we would almost certainly be talking about something that would have been using cpython, so it's relevant.

Not 'technically' at all. If it's normal python code, and the GIL is the problem, then you can change the interpreter and still use the code. But for something built on node, you can't just pull out node.