I'm not sure that DF's learning curve is really comparable to vi. Maybe TECO. Almost everybody's first fort dies because they didn't set plant orders or ran out of booze or something similar. Next, forts die because you got enough wealth to spawn an ambush and you are totally unprepared. There's a litany of failure conditions that can shut you down hard and once they've begun it is very difficult to impossible to reverse; tantrum spirals are the most obvious but for example you might find out that you needed to plant food some time ago, or that aquifers are full of Fun and Exciting and cause interesting problems for your nascent fort. I mean as a veteran I'm pretty good at avoiding these and getting into the late game but I can't even remember what they all are.

It reminds me in some ways of the old HGTTG text game, where if you didn't take exactly the right steps at the start of the game you would be irreversibly fucked two hours later with no warning. Except I think that was due to malicious intent, and DF's complexity is some combination of developer indifference / incompetence (Toady is quite good but obviously UI design is not something he's really enthralled by) and Stockholm syndrome on the part of the player base. Some folks won't play without Dwarf Therapist, I absolutely require dfhack's workflow plugin to not go insane, etc. This is not really a good situation, but there's just one of Toady and the community is startlingly loyal, probably helped by the sheer addictive quality of the game once you get going; he can be excused, to some degree, a focus on new, novel things before the total UI revamp needed.