Reddit has an absolutely massive wealth of community knowledge. If you want to find a community for $thing or gain obscure knowledge on $thing, that’s where you go (assuming there isn’t an old forum post from before Reddit killed forums).
Twitter is where a lot of people still are. If you’re the kind of person to care what a particular person says, that’s where you probably want to be.
Instagram is used by young people who have friends on Instagram.
It isn’t a great system, but it is the system that we have today. This is why legislation compelling Meta/Twitter/whothefuckever to act in an ethical manner is important. Social media is to some extent a natural oligopoly, and unless we get extremely, extremely lucky, the fediverse will always be a niche community.
Eli5: your PC has different access levels a program can run at. This prevents a malicious or badly coded program from completely fucking your computer. Kernel level anti cheat runs at the lowest level access that exists under windows. It can do basically whatever it wants to your PC, and if a backdoor is coded in (happens way more than you’d think), it gives malware basically total access to your PC.