It sounds like you're just nosy, then. The content of my LinkedIn profile is no more your business than the content of my Tinder profile, and just as relevant to my work.
What? LinkedIn profiles are literally about your work.
It's not about being nosy. It's about noticing inconsistencies. If someone is going through the trouble of maintaining a LinkedIn profile but they're also listing a different company as their current employer, it's time to start investigating.
LinkedIn isn't the final say, obviously. However, it can act as a canary in the coalmine for further investigation.
Empathetic managers trust their employees when they say a task is difficult and will take longer than expected.
Double job workers (and slackers in general) thrive on taking advantage of this empathy by lying and manipulating their way into perceptions that they are doing more work than they really are. Not fair to the manager, company, or team mates.
It's basic due diligence of any manager to check these things.
Tell me honestly for a second: if you weren't happy with someone's work, would anything on (or not on) their LinkedIn profile make any difference to that situation whatsoever?
The LinkedIn point was about looking for clues that you might need to investigate further. I think you're trying to twist my statement into something else entirely.
"Have curious conversation; don't cross-examine."
"Please respond to the strongest plausible interpretation of what someone says, not a weaker one that's easier to criticize. Assume good faith."
And some of these cases have been egregious:
https://news.ycombinator.com/item?id=29668822
https://news.ycombinator.com/item?id=29668427
Those kinds of comment are bannable offences on HN. I don't want to ban you, but this has been a problem many times before, and we need it to stop. Can you please review https://news.ycombinator.com/newsguidelines.html and stick to the rules in the future?