The core problem that LinkedIn solves has nothing to do with all the "social media" style content that plagues the platform. It is a long-term rolodex to be able to talk to former co-workers, while also getting contacted by recruiters (double-edged sword that that is), and for that purpose works just fine, even allowing you to ignore the other warts.
So if you were going to build a competitor, you'd need to get everyone who has built a profile on linkedin and built a 20 year rolodex of their network to all migrate away.
I'm not saying it cannot happen, I'm saying it is not a tech problem, so building a new flavor of the same app and hoping it wins out is an even higher-risk bet than most startups, and therefore does not fall into most people's risk tolerances.
So if you were going to build a competitor, you'd need to get everyone who has built a profile on linkedin and built a 20 year rolodex of their network to all migrate away.
I'm not saying it cannot happen, I'm saying it is not a tech problem, so building a new flavor of the same app and hoping it wins out is an even higher-risk bet than most startups, and therefore does not fall into most people's risk tolerances.