It does but there's a paid-army of coders/designers,
Back to a hobby project, In my case of a quest to an open source engine Wipeout named WXX Rebirth,
Beside bigsnake that rolled out his engine a while ago but for numerous reasons I didn't extend because in the mean time I've RE-ed the rest of files; there were a few people with access to the repo. but nobody ever committed anything, so I've been alone the whole time and the project simply stalled, even though all assets were already available (though they had to be rolled out differently since it's PSX formats). Even more, there's not even any motivating posts from users, let alone people that would actively participate ...
So you have an ideal but then there's reality, and unless people are paid, very few if none will get in the game. The exception is BNG and it's where people have drifted to.
Tip : grab as many trustable ppl as you can first, then start consider dreaming
Nothing personal, bro, it's just my experience I was extremely optimistic with in the beginning, then reality brought me back I guess almost 3 years now on ... I worked my ass off reversing formats, get the infrastructure up but no real game is up to now and as time is passing it's waning.
Personally I'd summarize all of your steps to 5:
-get ppl that will really work on the project
-get the assets up,
-build a preliminary engine,
-implement a real game skeleton (menu, sound etc ...),
-polish
(and with UE4 your a raising the bar very high for potential committers: C++, expertise, lot more time than C#/Unity, even though I know C++ I still find UE daunting)
ps you have a preliminary demo here : http://www.wipeoutzone.com/forum/sho...cial-Edition-!