Frostbite Engine is moddable:
Problem is, EA's "ANT" animation systems and the like aren't licensed, to where Frostbite's editor will never be released. To where people have had to try to reverse engineer it (a la that BC2 video above) and do "Project Venice" (Oh wait that was DICE's internal codename for BF3), to allow mods and stuff like that on a "pirate" server (airquotes for something that technically is "illegal" but possible to use).
Reading between the lines about the BioWare and Visceral problems, along with some DICE admissions at GDC, the "Frostbite" that existed for BC2 and BF3 is definitely not the same "Frostbite" that they've pushed as a company wide "solution" to where even Madden is on it.
One reason is that very animation system problem. DICE wasn't making an engine for anyone else to use, they were making an engine to run Battlefield on the consoles, so it was fine to cobble stuff together that just barely works. Then EA said "everyone needs to be able to use this" and DICE was like "you serious?" The
Mass Effect Andromeda team ran into the fact that Frostbite had no built in animation system, they assumed there was some powerful thing, not a recommended plugin.
There was a suggestion by DICE that they pulled what Valve did with Source a few years ago when they essentially tossed out the original engine and restarted development especially the planning, keeping the basics and the name, and that's what was handed out to the rest of EA. If you remember, in Source's case it was supposed to be super modular and you could hook anything into it, except that never worked, and they never put together a proper map editor, they hacked things together instead. That was why they had to basically toss it out, and they ported all the games to the new version. It even causes minor differences in Half-Life 2. You can download a "backport" mod to put the old engine in. The console versions also had minute differences because like the lighting model was different for Orange Box forward, but PC versions never had it implemented.
DICE has also more or less said they intend this "Frostbite" to eventually be able to support mods/user content/etc. That the old one was never going to allow it unless they did what they did in the end and rewrote half of it.
Mentioning Unreal bring up another funny point because you often see posts on GAF/ERA that are all like "ugh, Unreal" when they don't realize that a lot of release games will only run on a specific version of Unreal 3 or 4, you can quickly get something up running on the other versions of course but you'll still have to redo a lot of work, even if it's in UnrealScript depending on what version development started on. A number of UE3 games arguably shouldn't just be considered as running on UE3 considering they're more like running on an iterated engine that started with UE3.
Borderlands: The Pre-Sequel for example is running on a second hand version of what Gearbox had left over after
Borderlands 2. IIRC,
Battleborn is too. The main "Unreal tell" has been the texture fade-in, but everyone assumed it was the lighting or BALD SPACE MARINE CODE because there were only like one or two middleware solutions running on the consoles last gen for years. (Ironically, DICE being one of the companies to ignore that and use an unfinished lighting solution that Epic eventually adopted as a default. To where people for years would deny
Mirror's Edge was on Unreal 3 instead of Frostbite.)
The ultimate example of this probably being
Call of Duty where everyone has spent years going "it's just Quake 3" and many times they promoted how it's a NEW ENGINE, and people found that it still had the Q3A base for stuff like loading maps or sound effects SO IT DOESN'T COUNT. When you probably can't take much of anything from
Infinite Warfare and drop it into the source released Q3 code and get anything to work let alone compile.
To bring it all together, it's also amusing that nobody complained about the fact that
Titanfall 2 runs on
Source like the endless complaints about the latest COD or Valve game "STILL running on" Q3/Source fill comment threads. (Although the most amusing thing is that neither Titanfall feels like it has the infamous "Source ceiling" effect. Even DOTA2 had it stick in the camera for a long time during beta.)