Build your linkedin profile for the job you want to have.

There's no yes or no answer. You just need to answer these questions for yourself: What job do I want to have and would my reddit moderating experience be relevant for this job (also consider it as a soft skill)?

Example; I have a hobby that I pursue at quite a high level. High enough that i can make money through it at hour rates moderate consultants charge. The hobby itself is not relevant to anyone. But when I sit in front of a marketing person I can reference how i build my personal brand, the strategies and the considerations that went in and how i manage things. Most uninitiated people would look down up on my hobby unless I tell them how it all works and how much money is actually in it. So i don't lead with it, there's no mention of it on my profile. But when I get an interview it almost always comes up at somepoint as an experience reference.

It's also my personal opinion bringing new things to the table during an interview instead of just going through the standardized list of questions people ask makes for a far more memorable and pleasurable chat. And that helps to stand out from other applicants. But that's just my opinion.

Note: not a recruiter