Best practices is also another one. I feel they take too little opinions on how to use the framework, and it's difficult to find a best practices source (think a book like Two scoops of Django). This can be jarring to beginners.
I get that they're trying to be configuration first, but... People who use frameworks like Phoenix are trying to escape the freedom of systems that take too few opinions.
Phoenix strikes me as trying to be Flask but also trying to be Rails. I'm not sure it gets that middle ground right.
On the prior knowledge assumption: the tutorials for Phoenix assume too much Rails knowledge. Where Rails takes a beginner friendly approach with RailsGuides, Phoenix immediately assumes you're moving from Rails and the docs can be confusing for that reason.
The docs are sometimes made exactly for people who use Rails and that's very annoying for everyone else.
2.I'll be keeping an eye on Ash, that looks fantastic. An API framework that feels like Rails or DRF would be a killer app.
As a note, it's also baffling to me that Phoenix is trying to go the Rails route and completely ignoring modern API development. There's zero tutorials, just a generator. I really don't believe in LiveView: moving the UI state to the server is just a recipe for disaster.
I feel if Phoenix doesn't try to move where the industry is heading (API-first), they'll rapidly fall into irrelevance. Rails can afford to take that risk, they're too big to fail.
Phoenix and Elixir can't. They're too small and the incentives to move are not huge. They didn't kill Rails.
4. I haven't written extensively about it, but you can read my journey at my Twitter account (link in profile). I haven't been too active though, taking a break.