Buuuuuut. In the end, I think Illich fail his own test. He claims to analyze systemic impacts, but fail to recognize the systemic impacts of his own solutions.
I always use the "speed" example for this. Illich basically advocate for more or less banning the use of any mean of transportation faster than a bicycle. The arguments do make sense actually, in a lot of ways, and it is important to keep these in mind. But he acknowledge that there are real use case for engine driven vehicules and fast speed, for things like medical or emergency needs. Make sense right?
So from his pov, noone should have engine car, except for ambulance, medical transportation (like transplant), fire engine, etc. Where it becomes a net good.
What he utterly fail to realise is that without the fast transportation and the whole system built to ... actually build and distribute these cars to everyone, then building these emergency vehicules and developing the engineering for them cannot happen.
Not only it is cost prohibitive (because of reuse of means of production, mass production impact on cost, etc) but also it is really hard to actually engineer this stuff without a lot of experiments and needs for it, which do not happen if you restrict the use of these stuff to a limited niche.
Engineering need practical use of the tool to be able to learn about the use to make it more efficient and better to the point that it benefits everyone. That of course does not negate the point that these technologies do have negative impact on society. But thinking that you can wholly separate the positive from the negative, banning the later but getting the former, is not as simple as calling it out. You need to consider the systemic effects and really think through the long term and systemic impact of your action.
Something that Illich seems to only apply to other people actions, but not to his own remedy or analysis.