I agree 100%. I wrote something similar in this post, and we discussed the package ecosystem a bit over in that thread.
To summarize: I think the solution is that we, as instructors using Julia, select a few packages for the purpose of teaching undergraduates and standardize on those for education.
In my opinion, there is an easy part and a hard part to this. The easy part is putting up a “Julia for Education” website somewhere listing the package selections (and other tips for students). (My hope is that we could have a unified source that replaces the “beginning of class Julia quickstart” handouts we all write individually, which needlessly duplicates effort.) I would be happy to do this if there is sufficient interest.
The hard part is making sure those packages are easy to use and bug free. So, for example, it seems someone would have to write shift-and-inverse for one of the two packages you mentioned.
However, I think completing the easy part would help focus attention on what needs to be done for the hard part.
If you would like to discuss further, please let me know and I can create a new thread.