You've never been in an IDE, tried a go to definition, and have it not work?
I can think of a few cases where Rails architecture would be relatively difficult for IDEs: ActiveRecord callbacks, and of course metaprogramming and magic methods like "find_by_x".
In most cases this sounds like a mismatch between IDE and framework, but the "method_missing" chain could be a unique challenge.
I avoid using that construct in application code, and just accept that some of it exists in the framework -- but that it's almost certainly not the cause of any problem I'm debugging.
You get used to it, but it shouldn't be like that
What framework/language/environment can you think of where a junior dev can be dropped in to a big project, and not flounder?
With Go and Phoenix, this problem is not there. They are very explicit, so when something unknown is found, it's written there what it does.
With rails there are things going on at all time: write a record? Some stuff is written on the db, other stuff is triggered, some stuff depends on thread variables, then other stuff is magically saved in other tables, other is updated (touched), which in turn might trigger more things. It is painful for a new developer because all of this happens implicitly.
But I think I understand your point. You can ask a neighbor to "run to the market to get bread and milk" and expect reasonable results -- but you'll need to be more explicit with a foreign visitor.
Rails optimizes for neighbors, but in fairness the phrasebook and guidebooks are excellent. :)
I read this a lot, but I have never experienced it, even on projects that I have joined after they were already huge.
Rails conventions are pretty reliable. Most Rails developers choose predictable patterns that resemble the framework conventions. Obviously people coming from other frameworks will often build things differently (sometimes fighting Rails to do so), but a few minutes in the REPL makes everything clear.