It's very difficult to play the guitar, and takes a lot of dedication to really play it well. I think that after someone gets callouses on their fret board hand and gets those muscles in those fingers used to stretching out and making the basic chords - that from there it gets a heck of a lot easier.
What mostly matters, I think, is what exactly someone's goal is - I think most anyone could and should be able to learn the basic chords and strum along in time behind either themselves or someone else singing - not that that is easy, but it's definitely an attainable goal - playing leads like Al Di Meola or Tony Rice....that kind of stuff can be next to impossible for most people unless they dedicate ...say, five hours or more almost daily for a number of years to playing guitar.
You don't have to do anything like the speed picking to really enjoy playing though.
I wish that I could sing a lot better, if I could, then I'd play chords and sing all the time.