The general problem with doing gigs "for exposure" is that it typically only gets you other gigs "for exposure".
edit: should add that not only recruiters were there. Amazon engineers including their head of robot R&D were involved and available on the floor. Nice people.
(I'm not affiliated with Amazon and I don't do picking research)
Pretty much the only one I spotted in the team list that wasn't, was mitsubishi. Unless they're really struggling these days, I don't think that exposure is an issue.