system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What are the main reasons for the lack of state-on-state warfare today?

With few exceptions (e.g. Iraq and Georgia), there has been very limited direct state-on-state fighting in the last couple of decades. What are the big reasons for this? Is it the sheer power of militaries like the USA's  that makes fighting against their allies  (who make up a big chunk of nations) unthinkable, or is it more to do with things like dependence on the global market and threat of isolation?

A kind of extra point: when I read about modern armies, it seems a lot of equipment we spend lots on would only be used in a conflict of two advanced states, like anti-ship missiles. Why is so much spent on this, given I can't imagine it's been used since something like the Falklands? I'm assuming people will say it's because of this investment that these wars don't happen (deterrence), but even without the very latest torpedoes, aren't the massive sanctions, etc, enough of a deterrent to stop a state-on-state war?
gpt
South western Africa has been in a brutal war for decades. You don't hear all about it except through documentaries. Its mostly warlords fighting over diamonds, gold, silver, and other precious metals.