If the "joined XXXX" were put next to my name it would show I joined last August.
Yet my alter-ego Bucharest joined in 2004. She has just deregistered a lot over the years and joined up again.
The "joined in..." thing is wrong on 3 counts, the first ^ there, it's meaningless.
The second is that the very worst trolls that have passed into MN folklore were "long term (and often) well-respected MNers". There are several right now, here, as we speak, totally convincing, totally trolls.
The third is that that would give a nasty sense of hierarchy to the site, which frankly, is often pervading enough as it is. I can just imagine the sneering from the "hellairrrrrrr did you call" lot when someone with a "joined 2016" badge dares to encroach upon their territory.
All HQ can do, is ban ban and ban some more.
Namechanging could be banned. So, the troll would just sign up with another email account.
While we're at it though, there should be a ban for socking as well. Half the time the trolls are bumping their own threads and talking to themselves to ramp up the drama.
If I was queen of the world, I'd also suspend any thread (however gentle and nice) where people started talking about meeting people in the middle of the night, mercy dashes by MNers, handing over of food parcels. Let them do it in a PM, they know how it works. Trolls thrive on the fact that everyone is being drawn in to the drama as Batman and Robin leap into action. It'd soon die a death if it had to be done in private.