There’s a limit to the amount of space in the gig description and there’s a limit of 10 questions in the FAQ. Also buyers don’t always fully read the description.
eg. In a gig I say right near the top that I use software X for that gig, and I get a message saying they have a project and I must use software Y for it (which I don’t have). That’s another place where an auto-response could have been used - I’d already said I used software X in the description and they didn’t read it. If I’d mentioned software Y anywhere in the gig to say I don’t use it that would have helped find the gig if anyone searched for that (giving irrelevant search results).