To me, "pk boosting" is killing players specifically to raise your stat. I mean, that's what you're doing, boosting your pk stat up. I'm not saying it's a bad thing, and having a "pk goal" is fine. The thing is, whether you're pking at a tower or in a mob, it's still pk boosting. It's just as Colin said, it's just swinging your sword and hoping to get a kill out of it. When mod's full of people in the flag room, it's basically the same thing as swinging at a mob. Some people have the mindset of doing it in the most efficient way, using pk techniques, but I'm sure there are people using those same techniques at the mobs.
"Pk boosting", aside from the illegal way of pking the same person over and over excessively, is really just a mindset. I'm pretty sure most of the more skilled pkers do it for fun; for sport. They don't do it for the numbers, or so I assume. If people want to boost their pk stat, then why not do the most efficient thing and pick off people from a big mob of people? My pks are just from towering, so I don't really care either way. If people want to stand unmoving in a mob and spam their sword, it'll be extremely boring, but so be it. Just don't complain saying things like, "Hey, he/she has a lot of pks! But wait, he/she pks at mobs, I don't like him/her!" If you want to pk the fun way, then good for you. Other people, who just want to increase their stat, maybe they'll make use of this video.
Anyu got 800,000 pks in 2,000 something hours. It's still an accomplishment, and she didn't cheat or break the rules. If you want a large pk stat like her, then go ahead and pk as she did. If you don't want to do it "that way", then just pk your own way, as long as you're having fun with it.