Designers and even many developers found it essentially impossible to use and the developers who were reasonably comfortable with it spent way too much time assisting others in attempting to use it.
(fwiw I found myself somewhere in the middle - I like the model and understood the ideas but also found it annoying to work with in practice)
However, since my interests vary considerably, and therefore I dabble with lots of different tools, the difficult-to-learn tools never get enough traction in my limited human memory to get me to the easy-to-use stage.
If a community doesn't want to engage occasional users, it's probably fine (maybe even desirable) to have a higher barrier to entry to make daily use really fast.
If a community benefits meaningfully from occasional users, a high learning barrier may not be a good thing.