You would be surprised what people do with this kind of information. You've obviously never heard of being doxxed I guess.
I remember a few years ago having my phone number used by some a-hole who didn't like my replies to his gun control BS on a major site. He found my home phone (and with that my name and address) and used a hacked robocall system to send super-racist robocalls out using my name in the message and phone number as the caller ID.
I had no idea this was happening until I started getting angry calls on a daily (or nightly) basis from people who were offended by 'my' message. I have no idea what was said on it beyond being really racist, but it had people foaming at the mouth.
This went on for months and I eventually ended up simply changing the number to stop 2AM phone calls ranting about how I was racist scum and deserved to die.
As for gun serial numbers, I'm not sure what you could do with them.
I usually do blur them 'just because', and in another thread I mentioned a USPS inspector requesting I confirm one on a gun I sold here that ended up in CA illegally.
I can't really see the harm in showing them, but I also don't see the need to put any extra information out in a public forum that anyone can see.
