To emphasize the dynamics: (1) No person will migrate until most of their connectors migrate, and their connectors cannot migrate until everyone does. It's deadlock, for every thread you care about. (2) Automation in job applications and a declining job market have both made networking more essential, so there's no tolerance for lost connections, so you'd also have to solve those problems too before all would switch. (3) Even if users don't like it and could surmount the coordination costs of switching, if companies continue to rely on it, switching would be a career-limiting move; and because companies cannot signal their recruitment strategies without triggering a stampede to game their system, companies tend to keep quiet, so no company would lead an exodus.

Still, no one (outside influencers) likes how work networking and recruitment happens today, so user might do both linkedin and some new system if one created a more effective networking and recruitment mode (e.g., for some well-defined, high-value subset, like recent Stanford MBA's, YC alumni, FinTech, ...).