It has nothing to do with being Uberleet, or anything like epeen.
it comes from the fact that only a small subset of the people playing the game take advantage of how all of the tools the game gives for individuals to take advantage of.
Take a look at the "state of play" thread.
If you win the first engagement, getting a few kills among 3 or 4 people, you will likely win every single engagement after that as you have the ability to accelerate your money.
First you have your Uller, then you have your warhammer, or just jump straight to a Novacat and ride the rest of the game in cruise control.
If everyone did it, the games would be frustrating for those who realized they were on the losing end because they would realize their opponents reached the "pinnacle" mechs, and were using either the very aggressively powerful brawlers, or they were already using novacats or the extreme LRM boats.
Then they would quit, and that would be that.
It is because the most effective mechs in the game don't have the corresponding graduated income scale that they need based on the effectiveness of various weapons available in the game.
Better than patch 2.0 though, in that only a small handful of mechs were usable because they nerfed autocannons so hard. Sure, people in 2.0 running around in autocannon atlas mechs THOUGHT they were being effective, but unless you were using an HGAUS mech or a laser death machine (awesome or Novacat) you were toast (of course of course unless you were in a specific role mech such as LRM vulture, but from a KDR perspective LRMs dont provide as you can avoid them by ejecting IMHO).
Right now though there are a group of people who are figuring out how to play the game as it currently is, and they are going to have insane KDR's. This version of the game has massive amounts of armor on the mechs, if you engage at maximum range of your weapons and are in properly chosen mechs, you have little to fear from dying.
Most of the time I die lately has been because I have been extensively trying out brawler mechs, there has to be a method to make them work, and I tend to use the warhammer a lot as well.
Or when someone somehow sneaks on you with a madcat Mk2 or an atlas with autocannons lol.
Its harder to avoid "sudden" deaths in 3.x series than it was in 2.0, but "sudden" deaths dont come too often in this game, so the KDR can still be, easily, 5-1 or 3-1.
The most frustrating game I have had recently was when a small core of the opposite team was actually playing like myself and my friend do, and kept retreating after taking a few shots (on thunder rift) and the game ended with everyone only having like 4-5 kills max, and that was after 40 minutes or so.
This game can be this amazing tactical and strategical experience (because of the cost of mechs, and the fact that there is no mech lab) and very few people play it that way and instead run into each other like maniacs.
Which makes it so that those who do play it as a tactical/strategic game, who plan out there mech choices etc..., have high KDR games.
Skill has little to do with it, as long as you can hit someone with your gaus laden uller, and fire your ac10s when you get your warhammer, and can target well with your novacat, your good to go, at that point its all about being careful and running when you take too much damage too quickly.