In this case, it's perfectly technicaly feasable to figure out who wrote that node: we log IPs.

Anonymity is an arms race. Logging IPs is just a first strike. Not a good strike (multiple people behind a proxy, people behind multiple proxies) to begin with, and parried long before perlmonks existed. Apparently, the original poster wasn't taking any steps to defeat IP logging, but if someone wants to, it becomes harder to lift anonymity. I guess the OP cared about his/her XP, but didn't care that much.

Abigail