LinkedIn presumably tells its users how they are using the data, at least if they follow the law. Shouldn't people be allowed to consider those terms to be acceptable without it meaning they lose all protection?
"But it's impossible to protect your data against all re-use", you'll say, "someone may remember it". That is not just obviously true, it is the only reason one might want the protection of the law.
Things that can easily be prevented by technical means do not need to be prohibited. That's why the common argument that "it's your own fault when you are raped at night, in a park" or that someone stole your car when you accidentally didn't lock it is so absurd: laws aren't so much about preventing you from being raped. In the absense of the law, you'd just never leave your (fortified) appartment. Laws are about allowing you to go outside, to not spend your money on steel-reinforced doors, to leave your convertible parked with the top down.
"Might is right" just leads to a pointless arms race: social networks waste money on protecting against scrapers. They'll hide everything behind logins or paywalls. Scrapers will waste money on overcoming those protections.
If the scrapers win, some people will decide not to do something they would have otherwise done. In other words: they have become a bit less free. The social network becomes less useful and might shut down. The scrapers find themselves with nothing to scrape. Congratulations, everone lost.