He's right though, I've never done any animating or posing before in anything like honey select, blender, etc.
However, in Wild Life with just a bit of practice I was able to create custom characters by manipulating bone position and shapes, importing meshes, and finally pose and animate them however I chose. The animation sequence editor seems to be the same key framing setup you'd see in any typical animation tool.
Like he said before, if you look in the Discords, while you can see a range of skill or time spent, you have various examples of people making custom characters, all the way down to editing face and body structure/shapes and custom meshes. To people have made high quality animations similar to the ones the game has. Funny enough, even before the animation sequence editor was added, there were a few people that managed to make realistic animations just using transformer objects attached to the bones of characters. The game also has Lua scripts and other event tools. So, there's nothing limiting anyone from doing anything really, it's just all about how much time or effort someone is willing to spend. You could whip up your own choppy poor animation within 15 minutes or spend time just like the developers do creating a high-quality animation.