It's the nature of the internet and anonymity. There will always be trolls, some with significantly more time on their hand than others.
I don't get stressed out about it, because it's not a job. We don't get paid or receive any sort of compensation. I originally applied to be a mod because I've enjoyed GameFAQs for years and wanted to give back to the community. That being said, some days I don't mod or even post anything, other days I get through quite a bit of the queue and post left and right. I'm a user first and a mod second.
As for your question: Any mod can set a user to Warned. A lot of things go into deciding a punishment, and Warnings are typically only used for major violations. Only Admins can set a user into Purgatory, and the length of time the Purgatory is for is at the Admin's discretion. I'd go into more detail, but a lot of it is mod-only info unfortunately.
"I am for like it but on xbox, I did Titanfall as we were for cant destiny and Titanfall, side by side, I haven't much am for it, maybe seven?" - Over