That sounds tragically late to me. It represents a serious failure on the part of those who know and love the command line to make it accessible to newcomers, imo.
nmcli is more abstract than ip+iw+wpa_supplicant, but it's no more or less abstract than any GUI network configuration widget.
The output of ls is no more or less abstract than the contents of a directory as displayed by a GUI file manager. It's the same metaphor and the same information displayed in two different formats.
It's obviously different in some fields (like gamedev) where the code produced by the dev is not supposed to run in a linux environment.
Complete bullshit. The only thing it's a sign of is that you're not curious or passionate about linux.
Knowing about and being interested in linux may be a positive signal, but the opposite is not a negative signal.
Knowing linux is not a requirement to be a good professional programmer working in webdev.
And electron, don’t forget about electron.
That is also an extremely stupid requirement. You can be a good programmer (Especially as a junior) without knowing all the linux command line tools.