When I was a regular I used to get so pissed off at admins who didn't investigate RDMs or freekills when I was freekilled, and I would have to spend 45 minutes editing a video, uploading it to Youtube, and making a player complaint instead of the admin just dealing with it in-game. I did this for ~3 years before I got admin. Trust me when I say that I feel your frustration. When I got admin I made a promise to myself to never let anyone else have to deal with the BS I had to deal with as a player. In fact, I debated this exact topic with the higher-ups a month after I received admin.
But now that I'm on the other side of the fence, I started to realize that things aren't as simple as they seem. "Investigating" situations often means checking logs and mediating between two players. However, logs often don't reveal the entire situation and mediation between two players can only do so much before you're forced to make assumptions and potentially punish someone who didn't deserve it. Whether or not admins investigated in the past is irrelevant. Thinking about it from our point of view, we'd have to make assumptions to punish players who may not have even deserved it. This is why admins can only punish for situations they saw. If an admin fucks up and punishes someone who didn't deserve it, they'd be punished themselves.
I get it. On other servers admins investigate and try to go beyond mediation to actually come up with a punishment. But at SG admins are held to a pretty high standard and actions do have consequences. While it's time-consuming, the most clear-cut way to get someone punished for continually rule-breaking is to whip out OBS, record, and make a player complaint. I'm sorry for that, but we've tried many ways to make it as easy as possible for you by having admins frequent Teamspeak, shoutbox, and Discord, as well as installing calladmin on our servers. Hopefully these options help you realize that there's a lot more involved than there may seem to be and we've tried to make this process as painless and accessible as possible.