Looks like not everyone disagrees with me. Talent is probably only a limiting factor at the extreme levels. It's not like chess concepts are inevitably beyond most human understanding; it just takes work and experience.
Lack of talent also limits the speed at which you are able to learn. I know from experience that I can learn some things in minutes that takes other people hours. I also know that some other things are extremely tough to wrap my head around that others find more or less obvious.
I know chess and IQ aren't related, but chess and genetics may be.