Yes, it's perfectly fine to be sad about your loss, I would too in your situation.
But not everyone here has heard of him, and a good portion probably only know him from in game. From what I see, you know him in real life and were probably quite attached to him. But this goes for nearly any "X died :(" thread because many of the people are going to say RIP and forget about it within a month. It just seems that most of the sympathy is just because there's a topic about it.
I'm just saying some people get too depressed over the death of someone who they have only talked to behind a screen. This is not directed towards you at all, it's a death you've had to deal with personally. The point is all the general topics like this end up as a pit of sadness.
Pulling an example like "My cat died" out of a hat. I am 100% confident that the only person who was attached to the cat was the owner unless they happen to have siblings who are also on the forum. Despite nobody knowing about that cat until the topic, they all act like their own mother had died.
Plus, I think discussing deaths of close ones on the internet is of poor taste, but that's just my opinion.