The JupyterLab extension system is the biggest offender imo.
"Oh, I need to install the python package and the jupyter extension separately? And there are no breadcrumbs if I install one but not the other? And I have to figure out which versions are mutually compatible with each other and jupyterlab because 'everything latest' sure isn't? And I have to install extensions to get features that used to be built-in? And then I have to explain the install procedure to the person I'm trying to share with, twice, because he didn't believe me the first time? UGGGGGGGHHHHHHHH"