the answer to this thread is simple.
1. if you work in-house at a game studio, you will be expected to handle a large potion of implementation, and work with audio programmers to solve issues.
2. If you are a freelancer, you can probably score a gig just doing asset creation.
Well, I wouldn't paint with such a broad brush. I've had plenty of gigs as a freelancer where I not only took care of asset creation, I also did all of the implementation. In fact, I think that was one of the selling points to why I got the job. What you've stated above is certainly quite common but it isn't 100%.
Well, that's why I included "probably" in that part. I have had freelance and contract jobs where I did only asset creation, and ones where I had to do some implementation, and some where I had to do all of the implementation. I was just saying it would be much easier to find an asset creation only job through freelancing than an in-house audio job, but regardless, implementation and technical skills are going to be good to have.