Also, just this: NOT everything belongs to Epic. Only the things done using their own software or resources are, mind you.
Meaning that, if you make a texture or a model or anything else using a 3rd party software, unless you actually use it in a map (compiled unr package) or a mod (compiled u package), it belongs only to you and you alone, no one else, and even when compiled, if Epic takes your project and asks you the source or original files, you have absolutely all the rights to say NO (the ones 100% done by you of course, any "modified" resource from Epic belongs to Epic of course, but even in this case you only would have to give that small set of files, not everything), because the source belongs to you and you alone.
Also, belonging to Epic =/= belonging to the entire community unless an author wishes to.
The community is not Epic, and Epic is not the community, they're totally different things.
Since the very beginning of "free" coding and "free" projects (even before Epic Games existed), every developer did what he/she did for different purposes and different motivations: professionalism, attention, popularity, some just wanted to create stuff themselves, some just wanted to give stuff to people around, some just wanted to help, etc, etc.
As for my personal motivation, I simply enjoy doing what I do (creating new things and giving new experiences to everyone) and I want the game to live longer with new stuff. Personally, I share what I do, meaning that I finish my mods, then whoever wants to take content from there (skins, code, effects, models, whatever) is "generally" allowed to without having to contact me directly (notice that I emphasize the "generally").
Anyone with *original* stuff is free to "lock" it and take the stance "don't modify it please, at least without contacting me first" towards the *community*.
And at least I respect that, and if a developer says to me "don't touch it", I won't, even if I could and even if the "law" allowed me to.
This my friends, is called RESPECT, and is what keeps the world in enough order to progress and evolve, because we're all different, but try to bid by the same values, you break that, then there's nothing left but chaos, which means that in this case the community is no more.
You may not agree with locking or asking permission or giving credits or whatever the author asks you in trade for using his/her stuff, but if you don't respect it, you're one step closer for development for anything to simply shut down. Whatever the motivation, truth is you all use them without thinking on it, and fact is it exists at all because there was a motivation to begin with, whatever it was, where the author thought it was worth, and if we don't respect that, say good bye to more than half of all the projects open-source or free in the entire world, and say hello to more paid-only independent projects.