If the authorities weren't already aware of the identity of the person who posted that, what's stopping somebody with terrorist intentions from simply omitting that account while applying for a visa?
To me, this seems like a grave transgression of privacy with little to no actual safety benefits.
The point isn't that they'll provide it. The point is that a bunch of useless people buried in the bureaucracy can say "well, he wasn't on our radar and his social media came back clean" and act like that constitutes doing their jobs.
It's no different than your local government that's probably happy to permit all sorts of absurd invasive development as long as some engineer puts a stamp on it but if a homeowner wants to build a retaining wall he gets told to f-off and come back with $20k of engineered plans that make the project not worth it.
It's not about the end result. It's about dodging accountability.
People on Visas are guests, it makes sense to ask questions like this that wouldn't ask ordinary citizens. We have been way too relaxed with it and it's nice to see some changes.
To me, this seems like a grave transgression of privacy with little to no actual safety benefits.