LinkedIn is such a user-hostile platform with no value proposition to anyone who isn't in those two groups. You have a LinkedIn profile as a CV with connections as a kind of social proof and never think about it otherwise.
As for the "trick" in this post, it seems like every platform with a feed have this issue. I've seen people recommend posting Youtube Shorts and untick the box "send notification to subscribers" because most subscribers are dead accounts so if you do this Youtube thinks the video has poor engagement.