> asking them to perform actions they don't understand is a terrible idea both in terms of usability (because the process is difficult, intimidating and error prone) and security (because you're training them to follow instructions that can easily put their system in risk when requested by a malicious actor).

I think you greatly overestimate the understanding of nontechnical users. Why is

1) double click icon -> click here -> click there -> type in box -> click ok

usable and secure but

2) open powershell -> type command -> hit enter

not? My suspicion is a surprisingly large fraction of nontechnical users have limited understanding of what they're doing and just blindly follow instructions. What does it matter if they are doing that with a mouse or with a keyboard?

> If the actions to follow are really that simple, they should be automated in full; there's no reason why you would show the users anything more complex that a start button to trigger a script, and a confirmation dialog explaining the risks (and maybe requesting elevated permissions).

I completely agree.

> But if the process is not so simple that it can be automated behind a single button, then why on heaven would you expose them to an interface that requires a complex interaction (copy/paste various large texts from a web page), shows cryptic messages as feedback, and gives no clue on what to do next if any step has errors?

What, like this doesn't happen with GUI applications? Those problems have absolutely nothing to do whether an interface is graphical or not and have everything to do with bad usability in general.