To be honest I do not think you have played a hunger games match since 1.7 came out, the hunger difference is so huge it is very, very hard to miss.
And what you say about the SG players who don't use kits, I had 203 hunger games wins on the old leaderboards before I got my first kit, miq. I only had the kit MakeItQuick, because this was just a fun boost. Then the prize buff was added and the amount of kits you faced so sky rocketing. I got make it quick plus and complete control plus, because I already have a leggy computer, so I used these kits to be able to combat the other kit users.
As for vanishing, or kit spy, this kit is not OP and many will agree it actually hinders you, if you are invisible a wood sword will kill you in 2-3 hits, and this kits particles can easily be seen when invisible, the only true OP kit is buffer, a one hit should never happen.
And as for learning the maps, I only play hunger games 2-3 but I know almost every chest on the other maps, plus, I have 77 hours of survival games played so clearly me not knowing the maps and player strategies is not the issue, I can tell you the location of almost every chest on arenas 2 and 3 and also where the common players go on each of the maps and where to find them.