Nevertheless, reality is as it is.
So are the xenos.
In the same way as you don't see that many "christian avengers" walking on the streets of our wonderful world, you also don't see that many extremist, fanatic, "kill everything in sight" xenos.
You can also notice that once in a while, an independent group of xenos appears. Group of xeno extremists. They kill whatever crosses their paths. They also die out fast.
