The completely pointless 'skills' sections, where anyone can add whatever skills they like to their profile. Oh, you're skilled in 'Data Center'? How utterly meaningless.
Interesting. I find the skills sections to be really helpful. I understand that the signal is not official and not a certification of any type, but the endorsements give me a sense for the extent to which someone is known by their peers and colleagues for a certain expertise. That's useful when I need to get up to speed on someone very quickly (e.g., when they got CCed onto a call with me and I don't know who they are).